Joerg Prietzel:
Synchrotron-based X-ray Absorption Near Edge Structure (XANES) spectroscopy: A powerful tool toassess the speciation and cycling of important bioelements (e.g. S, P, Ca) in soils and otherenvironmental samples

Abstract:
Environmental effects of nutrient or noxious elements in soils are often dependent on their oxidation
state or binding form. Therefore, in soil science and other environmental sciences (e.g. geology, biology,agronomy) besides knowledge on total concentrations of a particular element under study, additionallyknowledge on its binding forms in the investigated soil or environment is important. Traditional wet
chemical methods of soil analysis most often allow only for a operationally-defined estimation rather thanexact quantification of the respective amounts of different forms of a given bioelement in soils.
During the recent decades, synchrotron-based X-ray absorption spectroscopy methods, namely X-rayabsorption near-edge structure (XANES) spectroscopy has emerged as a powerful tool for theidentification and quantification of different binding forms of various bioelements with relevance in soils
and other environments. However, application of XANES spectroscopy in soil science is particularly
challenging, because soils compared to well-defined materials such as alloys, stones and rocks are often
characterized by low concentrations of the element of interest. Moreover, the composition of soils often
is poorly defined or even unknown, which complicates the selection of appropriate reference compounds
for spectrum deconvolution and/or spectrum deconvolution itself.
In my talk, I will present several studies which demonstrate how synchrotron-based K-edge XANESspectroscopy can be used to reveal the speciation and cycling of various bioelements in soils, forest, andrangeland ecosystems. The examples include (i) studies on sulfur (S) and iron (Fe), which most often insoils are present in different oxidation states, depending on soil water saturation. Moreover, I will present(ii) studies on phosphorus (P) speciation in forest, rangeland and glacier forefield soils. Application of P Kedge XANES spectroscopy on soil samples is complicated, because soil P contents generally are low and Pin soils is almost entirely present in only one single (+V) oxidation state. Spectral feature differencesamong different P forms in soils therefore often are not prominent and sometimes even absent. Finally, I
will present novel results of (iii) a recent study on Ca speciation in forest soils. Here, particular binding
properties of divalent Ca cations impose new methodological challenges for spectrum deconvolution.

References:
PRIETZEL, J., THIEME, J., NEUHÄUSLER, U., SUSINI, J. und KÖGEL-KNABNER, I. (2003): Speciation ofsulphur in soils and soil particles by X-ray spectromicroscopy. Europ. J. Soil Sci. 54, 422-432.
PRIETZEL, J., THIEME, J., EUSTERHUES, K. und EICHERT, D. (2007): Iron speciation in soils and soil
aggregates using synchrotron-based X-ray microspectroscopy. Eur. J. Soil Sci. 58, 1027-1041.
PRIETZEL, J., TYUVEKCHIEVA, N., EUSTERHUES, K., KÖGEL-KNABNER, I., THIEME, J., PATERSON, D.,
McNULTY, I., DE JONGE, M., EICHERT, D., SALOMÉ, M. (2009): Anoxic versus oxic sample pre-treatment:Effects on the speciation of sulfur and iron in well-aerated and wetland soils as assessed by X-ray
absorption near-edge spectroscopy (XANES). Geoderma 153, 318-330.
PRIETZEL, J., BOTZAKI, A., TYUVEKCHIEVA, N., BRETTHOLLE, M., THIEME, J., KLYSUBUN, W. (2011): Sulfur
speciation in soil by S K-edge XANES spectroscopy: Comparison of spectral deconvolution and Linear
combination fitting. Environ. Sci. & Technol. 45, 2878–2886.
PRIETZEL, J., DÜMIG, A., WU, Y., ZHOU, J., KLYSUBUN, W. (2013) Synchrotron-based P K-edge XANES
spectroscopy reveals rapid changes of phosphorus speciation in the topsoil of two glacier foreland
chronosequences. Geochim. Cosmochim. Acta 108, 154-171.
PRIETZEL, J., KLYSUBUN, W., WERNER, F. (2016): Speciation of phosphorus in temperate zone forest soils
as assessed by combined wet-chemical fractionation and XANES spectroscopy. J. Plant Nutr. Soil Sci. 179,168-185.
PRIETZEL, J., KLYSUBUN, W., COLOCHO HURTARTE, L.C. (2020) The fate of calcium in temperate forest
soils – A Ca K-edge XANES study. Biogeochemistry 152(2), 195-222. https://doi.org/10.1007/s10533020-00748-6