In my opinion, the reliability/quality of measurement results of water samples depends on strict adherence to each step of sampling, preservation of samples, time-interval between sampling and analysis for filtered but un-acidified water samples, and on the methodology adopted, and not simply analyzed by any person or lab or any technique.

Interpretation and conclusions based on such unreliable results for uranium

analysis will be highly misleading.

The application of software  for geochemical modelling will give a more meaningful interpretation /direction with a set of reliable data.

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a report on groundwater quality around and downstream of non-so-hidden U bodies you find under my documents

Best regards

DPS Rathore has provided U the best possible answer and comments to help U. We used both hydro-geochemical and bio-geochemical surveys for U determination in water of Punjab Siwaliks and lower Himalayas but prepared no model as these were random surveys. Please visit Researchgate to find our publications. 

In multivariate analysis, an interesting situation arises when we have , e.g., K element in ground water and we normalize data before calculating correlation matrix, it may be bimodal distribution and we won't be able to normalize the data. What do we do then?

Analyses of the short-live radioactive isotopes of the U-238 and U-235 series can provide a very good insight. E.g., Rn-222, Ra-226, Ra-223.

A hydro-geochemical uranium anomaly  provides a proxy data/inference, for possible uranium anomaly. It could be difficult to utilize the same for uranium ore-body characterization , in quite a lot of  cases, like deep-seated uranium ores, since this is based on far-field radioactive signatures (leaching of radium and its subsequent transport/migration). Such data needs to be integrated with subsurface geophysical studies, based on the depth of investigation. The latter are quite useful and reliable being non-invasive and the availability of robust joint inversion techniques,  for radiometric and elecrical/electromagnetic data or radiometric and seismic data, for delineating the source function. This could also be well supplemented with selective geophysical logs and coupled to geostatistical ore-body modeling for uranium ore bodies.

I would like to thank you all for your interest and contribution to this topics.

I am very grateful to D.P.S. RATHORE who provided a lot of information and references. With respect to the sampling, the data we used for the multi-variate modeling came mostly from C. Beaucaire, and described in "Redox chemistry of uranium and iron, radium geochemistry, and uranium isotopes in the groundwaters of the Lodève Basin, Massif Central, France" Applied Geochemistry - APPL GEOCHEM. 01/1987; 2(4):417-426. , (she is on researchgate).

Techniques have certainly improved in the meantime, but it was what we had best for the time and this was supervised by CEA/COGEMA. I have no particular skill in geochemical sampling and rely on their work. Catherine Beaucaire also defended her PhD Thesis on this and the document - though in French and available - contains several papers in english (including the one aforementioned), title ""Geochimie de l'Uranium et du Radium ; Desequilibre Radioactif dans les Eaux Naturelles". Would you need the documents, she'll certainly provide them or I can help would she be busy.

What I have noticed, reworking on this, is that the pure multi-variate modeling matches the redox fronts that were identified by "pure" geochemists. When I first acknowledged it in the early 1990 and tried to publish that in the French "Comptes Rendus de l'Académie des Sciences", I was rebuffed on the basis that the abstract mathematical modeling of geochemical processes was meaningless, as I could not identify geochemical processes at work (redox systems at work, speciations based on Eh, pE/Log(a), etc.). Though this is correct, I do not believe it to be a decent argument, as the factor model identifies the same type of waters as Catherine Beaucaire did, and not only that but offers a theoretical spatial mapping of the redox front, which discontinuous geochemical samplings do not. As I do not give up easily when I have an idea, this is the subject of a future paper I would like to write, especially as the mining work is now finished in Lodève and all data are freely available.

I also thank Robert Kringel for his links, though he was not specific and I would appreciate if he could bring more precisions.

I'll visit Hardev Singh Virk's paper especially for the bio-geochemical surveys as this influences strongly the U speciation and mobility.

Thanks to Gilles Levresse, I'll read the paper with much attention.

As a preliminary answer to B.K. Bhaumik, the data set I used was somehow normalized and final factor scores were scaled to atomic masses of components to provide for electric neutrality of solutions and models (more in Un Système d'Aide à la Décision en Prospection Uranifère: Méthodes de Discrimination des Anomalies Géochimiques Multi-élémentaires Significatives - but the text is in French). I do not have specific experience with multi-modal distributions, that I've always tried to "segment" in simpler one by various tools (e.g. dynamical clustering, etc.)

As Boaz Lazar pointed short-lived "Rn, Ra" can be helpful, but again this was better studied on purely geochemical grounds by Cathering Beaucaire, among others, than I. I'll look closely at it.

Finally, Debashish Sengupta points to an even more difficult subject as the hidden deposits we were looking for in Lodeve were not deeply-seated. I concur that for deeper bodies non invasive methods would be of a great help (Fourier transform ? others ?). BRGM might have done some geophysics on the area studied, I'll check.

Would Debashish Sengupta have some examples of such non confidential studies where geophysical / geochemical and maths modeling have been made, I would greatly appreciate.

Best to you all,

Patrice.

Dear Patrice,

    If possible you could look at the Chapters in our recent Book by Springer "Recent Trends in Modelling of Environmental Contaminants".  In addition we ihave ntegrated In-situ Gamma Ray data, V.L.F. and Resistivity,  for Modelling of  Shallow uranium deposits. These techniques seems to work well in our recent studies on uranium mineralization in South Purulia Shear Zone (use the google search for the relevant publications) and the Singhbhum shear zone, Eastern India. We are very presently undertaking work on helicopter borne and air-borne radiometric devices and develop the Algorthim for joint inversion of the data. Other aspect we are looking into is the application of artificial neural network (ANN) for robust modeling of the data for delineating both shallow and intermediate depth uranium deposits

Dear Debashish,

Thank you very much for your contribution. You're far ahead in the area of coupling geochemical data and geophysical exploration. Processing of the data is also a key area that you work on with an original approach. NN might certainly be of interest. Developing expert-systems or KB-systems could also be a means of making a synthesis of all the knowledge and expertise you have accumulated, even if it just to help teach young engineers operating in an industrial environment the proper logic behind the usage of these diversified exploration techniques.

Thanks again,  Patrice.

It is believed that experience is a wonderful thing. It enables us to recognize a mistake when we make it again. The use of primary method or principle of the method in analytical measurement per se does not guarantee a reliable or metrologically

traceable result.

I have asked a question in my profile on: How to identify human errors in analytical chemical measurements and necessary measures to correct them?.

I would like to add here that some of the answers added by the researchers are worth appreciating and should be re-investigated in depth.