Ecological differention among closely related species may rely on minute environmental conditions, including in the soil. In the litterature, soil preferences are usually oversimplified, e.g., calcicolous, silicolous. I would like to use X-ray fluorescence to obtain more detailed characterisation of soil conditions.
Dear Adrien,
we did some similar tests just recently, and in particular heavier elements can easily be detected and quantified in XRF. Light elements (say below e.g. sodium, Z=11) are more difficult, as - even if the XRF experiment is conducted in a vacuum system - the soft X-rays are heavily absorbed already in the window of the X-ray detector, and the fluorescence yield is small for light elements. However, meaningful results may be obtained.
We did some testing of soils in the vicinity of our university, however employing electron excited fluorescence analysis in a scanning electron microscope. So you have the advantage that you get the morphology of the investigated soils as well. XRF may have the advantage that an "on-site" analysis employing a mobile, handheld or transportable XRF is eventually feasible (see e.g. https://www.amptek.com/products/exp-2-complete-experimenters-kit this system can be entirely powered by a PC and/or USB connections, or alternatively
https://www.olympus-ims.com/de/xrf-xrd/xrf-handheld/)
Hope this helps,
Best regards, Dirk
Dirk Luetzenkirchen-Hecht
Lieber Dirk,
Vielen Dank, this sounds encouraging. The elements I am especially interested in are: Ca, Si, Fe, Al, Mg, N, P, K. So if I understood properly, XRF should work for all except N (I can estimate it by other means). For my project, I am not sure the morphology of the soil would be useful, as this will be at high elevations, so mostly poorly evolved "Orthent" soils. Would employing electron excited fluorescence analysis in a scanning electron microscope help for such soils? I guess soils in W (I suppose) are more evolved. MfG aus K.
Adrien
This depends on the type of the device and its detector. But generally speaking, As Dirk pointed out, XRF does is not an accurate tool for the determination of light elements, as the references say, elements lighter than Na. We ourselves found difficulties in the measurement of elements lighter than Si.
So you can use standard samples and verify/calibrate your XRF. we did the same :)
Dear all,
What software do you recommend to do a quantitative analysis?
Thank you
Shadi Moshayedi and Cesar Escobar Claros
Thanks Shadi for your answer! I will not use the transportable version of the XRF (it was much criticised by a friend of mine), I thing it is going to be the PANalytical AxiosmAX machine. I was hoping that by having several measurements per soil sample, several samples within geographical sites, and several geographical sites the replication will offer a chance to deal with uncertainty especially with smaller elements.
Thanks Cesar, I cannot answer your question regarding the machine, but maybe Shadi can? For the data I am going to use the approach by Guggisberg et al. 2018 (DOI: 10.1111/mec.14930).
Best wishes,
Adrien
Adrien Favre my pleasure. Exactly we did the same. it is like drawing an in-lab standard curve for a specific type of samples.
Cesar Escobar Claros we use SuperQ. because of the age of our machine, there are some uncertainties, however, we used known samples, standard samples etc. to verify the results, or more precisely, to reduce the error.
Dear Shadi Moshayedi and Adrien Favre thank you for your indications.
Could you share a little more about your friend's opinion (limitations) of the portable version?
Cesar Escobar Claros : If I remember well, my friend mentioned that it is relatively heavy to carry, and not super precise. It is not as easy as it appears on the advertisement. Otherwise, you may contact Guillaume Cailleau here on RG, I believe he has some experience with it...
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