This study addresses the geochemical mechanisms of authigenic ferromanganese (Fe–Mn) ore formation within modern aeolian sands of the Lake Baikal coastal zone, driven by subaerial groundwater discharge. Despite the extensive knowledge of subaqueous Fe–Mn nodules, the terrestrial lithification of coastal sands remains poorly understood. We employed a multi-analytical approach—including X-ray fluorescence (XRF), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA)—combined with Q-mode and R-mode cluster analysis to decipher the paragenetic sequence and metal sequestration kinetics. Our results reveal that the cement consists of authigenic Mn and Fe (oxy) hydroxides formed at localized redox and pH-driven interfaces. A key finding is the identification of a natural self-organizing system functioning as a geochemical barrier that ensures the spatial separation of Fe and Mn phases due to differences in oxidation kinetics and microbial catalysis. This process represents a rare terrestrial analogue to hydrogenetic sedimentation, demonstrating rapid modern ore genesis. The study establishes that these formations act as a critical geoecological filter, sequestering heavy metals (Ba, Zn, Cu) before they enter the lacustrine system. These findings provide a fundamental baseline for monitoring anthropogenic impacts and understanding the biogeochemical resilience of the Baikal coastal geosystems, offering a new conceptual model for rapid epigenetic mineralization at terrestrial-aquatic interfaces.

We characterize apatite from the Slyudyanka deposit (Central Asian Orogenic Belt near the southern end of Lake Baikal, Siberia, Russia) for use as a new apatite reference material for elemental microanalysis. This apatite (SlyudAP) is a gem-quality crystal, with high concentrations of Sr, Th, and As, and intermediate concentrations of rare earth elements (REE). The following analytical methods were used for the characterization of the apatite sample: wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry and scanning electron microscope (SEM) with an energy-dispersive X-ray spectrometer (EDS) for major elements, inductively coupled plasma mass spectrometry (ICP-MS) after digestion and total-reflection X-ray fluorescence (TXRF) spectrometry for trace elements, and isotope dilution thermal ionization mass spectrometry (ID-TIMS) for U/Pb dating. Spatial homogeneity of SlyudAP was confirmed for major elements by SEM-EDS with RSD < 7% and for trace elements at the mu m scale by LA-ICP-MS mapping with combined spatial uncertainty Uc< 8% for most elements. Some minor inclusions of barite, which are located along cracks and can be simply avoided, have been found by SEM-EDS in only one of the eleven crystals. A comprehensive ANOVA performed on key elements (Sr, Y, La, Ce, Pr, Nd, Th, U, Pb) from bulk analysis of multiple fragments showed p-values >0.05 for all elements except Th, indicating no statistically significant evidence of between-fragment heterogeneity at the 95% confidence level. Interlaboratory LA-ICP-MS tests by six laboratories demonstrated good convergence. Based on comprehensive homogeneity testing and interlaboratory comparison, SlyudAP demonstrates sufficient homogeneity for use as a matrix-matched secondary standard for LA-ICP-MS analysis. Suggested and recommended values for SlyudAP are provided.

The determination of rare earth elements (REEs) and associated trace elements (Sr, Ba) in fluorite (CaF2) is essential for geochemical tracing of hydrothermal processes and ore deposit characterization. However, routine multi-element analysis often relies on costly and complex techniques such as inductively coupled plasma mass spectrometry (ICP-MS). This study presents the first application of total-reflection X-ray fluorescence (TXRF) spectrometry to the quantitative analysis of Sr, Ba, and REEs (Y, La, Ce, Pr, Nd, Sm) in fluorite. Samples were digested using a mixture of HF-HNO3-HClO4, and the resulting solutions with Ga as an internal standard were analyzed by TXRF. The method was validated using an in-house synthetic CaF2 standard, whose REE concentrations were independently verified by solution ICP-MS. For the synthetic standard, TXRF showed good agreement with ICP-MS for Y, Ce, and Pr, but systematic underestimation was observed for La, Nd, and Sm due to spectral interferences from overlapping L-lines in the energy-dispersive spectrum. Element-specific correction factors (k = 1.33-1.69) were derived from the synthetic standard to compensate for these biases. Analysis of five natural fluorite samples demonstrated that TXRF results for all elements were consistent with those from ICP-MS for concentrations above similar to 100 mu g/g, with recoveries typically ranging from 85% to 115%. The proposed TXRF method, utilizing a common acid digestion, presents a cost-effective and robust alternative to ICP-MS for the routine multi-element analysis of fluorite, particularly suitable for samples with elevated REE concentrations common in many hydrothermal and magmatic deposits.

X-ray fluorescence analysis of snow cover solid phase samples collected near aluminum smelter facilities is a promising method for investigating environmental pollution. Key issues in determining fluorine by X-ray fluorescence method in these samples are the lack of matrix-matched reference materials and the strong dependence of the FK alpha line intensity on fluorine's chemical state. To address this, we considered artificial mixtures for calibration, prepared from soil reference materials, alumina, and various fluorine compounds (such as fluorite, synthetic cryolite, and aluminum fluoride), along with reference materials of apatite ores and granites. Measurements were performed using a wavelength-dispersive spectrometer. The selection of optimal measurement conditions minimized the influence of spectral overlaps and other factors affecting the FK alpha line intensity. Artificial mixtures based on both aluminum fluoride and synthetic cryolite were chosen as optimal calibration set. For snow cover solid phase samples collected near the Irkutsk Aluminum Smelter (Irkutsk district, Russia), a comparison of the proposed X-ray fluorescence analysis method with potentiometry showed a root mean square deviation of 0.15 wt% for fluorine content range from 0.4 to 1.6 wt%. Furthermore, comparing the data from these two techniques allows for inferences regarding the probable chemical forms of fluorine present in analyzed samples.

An approach utilizing the intensity ratio of copper L-series X-ray emission lines was developed to determine copper mineral forms. Minerals containing predominantly monovalent copper as sulfides (chalcocite, bornite) and oxides (cuprite), as well as divalent copper as sulfides (chalcopyrite) and sulfates (antlerite, brochantite) were studied. A conventional wavelength-dispersive X-ray fluorescence spectrometer with moderate energy resolution (around 15-20 eV at the CuL alpha line energy (930 eV)) was used for measurements. This resolution is not sufficient to completely resolve the CuL(3 and CuL alpha lines. However, the ratio of the CuL(3 and CuL alpha line intensities differed significantly among various copper minerals: from 0.23 to 0.24 for cuprite and chalcocite to 0.43-0.44 for malachite, antlerite, and brochantite. Investigation of copper-nickel ores enabled the identification of chalcopyrite as the main copper-containing mineral, which corresponds to X-ray powder diffraction data.

The quality of total reflection X-ray fluorescence (TXRF) analysis data for S, Ni, and Cu in copper nickel sulfide ores has been assessed in the framework of an interlaboratory comparison program, with allowance for requirements that should be met by techniques for determination of the chemical composition of mineral raw materials. Certified techniques for analysis of mineral raw materials by this method are not available, and the results obtained in the interlaboratory comparison program were used to assess and improve TXRF measurement accuracy. Ore samples were prepared in the form of suspensions using wet grinding. The analytical signal used was the intensity ratio of characteristic lines of the elements to be determined and a Ga internal standard. To construct calibration curves, we used reference samples analyzed by certified techniques: Cu and Ni were determined by atomic absorption, and S by gravimetry. The quality of analytical data was assessed using the Z-criterion. The random measurement error did not exceed 5

Novel X-ray fluorescence technique is applied for determination of ferrous iron (FeO) content for reference material characterization in addition (or as alternative) to volumetric method. Approach is based on the dependence of FeKβ5 line relative intensity on the iron valence state. A set of 99 reference materials was studied to choose optimal calibration set containing rocks of different composition: ultrabasic, basic, intermediate, and acid igneous rocks, silicate sedimentary and metamorphic rocks. The ratio of FeKβ5 and FeKβ1,3 lines intensities was chosen as analytical parameter. A set of 40 GeoPT samples was analyzed, and it was shown that the uncertainty of proposed X-ray fluorescence technique is comparable to one of certified volumetric (potassium dichromate titration) technique for the samples with Fe2O3tot content more than 1 wt%. The presence of Sr and Co in usual for rocks content (up to ∼0.23 wt% and ∼200 μg/g respectively) does not affect to the measurement uncertainty. Analytical potential, limitations and features of proposed technique are discussed.

An overview of publications dedicated to the application of various X-ray fluorescence techniques for investigating the chemical composition of ancient ceramics and clays is presented. Examples of conventional wavelength dispersive and energy dispersive X-ray fluorescence spectrometers, portable X-ray analyzers, spectrometers with polycapillary optics (micro X-ray fluorescence spectrometry), and total reflection geometry are considered. Although X-ray fluorescence serves as the analytical signal in all cases, the listed X‑ray fluorescence techniques differ in the range of analytes, methods of sample preparation, and methods for calculating element concentrations. The author experience in applying the described techniques of X-ray fluorescence spectrometry to a comprehensive study of archaeological materials from the Stone Age for the historical reconstruction of economic activities in the Baikal Siberia population is also discussed.

The quality of the determination of S, Ni, Cu in copper-nickel sulfide ores was assessed in the framework of the program for interlaboratory comparative tests (ICT) using total reflection X-ray fluorescence analysis (TXRF) taking into account the criteria for methods for determining the chemical composition of mineral raw materials. Certified TXRF techniques for the analysis of mineral materials are absent, so the interlaboratory comparison test was used to control and improve the accuracy of measurements by TXRF. Powdered ore samples were prepared as suspensions by wet grinding: 100 mg of the powder, 4 ml of ultra-pure water and 250 μl of the Ga standard solution were milled using 20 g of ZrO2 balls 1 mm in diameter in the mixing mill for 10 minutes at a frequency of 20 Hz. The ratio of the intensities of the characteristic lines of the analyzed elements and the Ga internal standard was chosen as an analytical signal. To plot calibration curves, a set of ore reference samples was analyzed using certified procedures (atomic absorption spectrometry for Cu, Ni, gravimetry for S). The quality of the TXRF analysis was assessed by the value of Z-criterion. The measurement error did not exceed 5 rel. %. The relative percentage differences between the TXRF results and the results obtained in the interlaboratory study was less than 10%. The described method can be used for rapid analysis of copper-nickel sulfide ores.

A novel approach for quantitative analysis in total-reflection X-ray fluorescence (TXRF) which can be employed for the samples with complex matrices inducing overlapping spectral signals in the scenario of limited availability of standard samples is proposed. The approach is based on the least squares (LS) decomposition of real spectra into the weighted sum of simulated individual element subspectra and requires only a single sample of matrix-matched reference material. Oceanic polymetallic nodules and crusts, having complex mineral matrix and containing high concentrations of overlapping elements, were chosen to demonstrate the feasibility of the approach in quantification of 11 elements. The comparison of the results obtained with LS decomposition, internal standard and linear calibration with three standard samples was performed. It was demonstrated that the performance of the proposed approach and of the linear calibration was better than that of internal standard for most of the elements; however, the proposed method requires only a single standard sample.

Snow cover is an important source of data for the study of environmental pollution due to its ability to accumulate atmospheric dust particles. A total reflection x-ray fluorescence method (TXRF) was applied to assess the concentration levels of potentially toxic elements (As, Pb, Zn, Ni, Cu, Cr, V, Mn, and Sr) in samples of snow cover solid phase collected in suburban areas of the Irkutsk region with industrial activity. Suspension was chosen as an optimal sample preparation procedure for solid phases of snow samples obtained after melting and filtration. Results were compared with those obtained by wavelength-dispersive x-ray fluorescence spectrometry and atomic absorption spectrometry. Precision of TXRF results expressed by repeatability values was not exceeded 15% (n = 3) for most of the elements, and the trueness of the TXRF method expressed by recovery values was in the range of 87%-115% for concentration levels of 5.0-350 & mu;g/g. Forty samples of snow cover solid phase were analyzed by TXRF method and results were compared with the background values. The investigation showed low contamination of the studied area by Pb, Cu, V, Mn, and Sr, medium contamination by Ni, As, and Cr, and high contamination by Zn. TXRF is advantageous in being rapid, cost-efficient, and simple and can be used as a promising method for an assessment of environmental pollution.

Представлен обзор публикаций, посвященных применению различных вариантов рентгенофлуоресцентного метода анализа для исследования химического состава древней керамики и глины. Рассмотрены примеры использования стационарных волнодисперсионных и энергодисперсионных рентгенофлуоресцентных спектрометров, портативных рентгеновских анализаторов, спектрометров с поликапиллярной оптикой (микрорентгенофлуоресцентный анализ) и геометрией полного внешнего отражения. Несмотря на то, что аналитическим сигналом во всех случаях является рентгеновская флуоресценция, перечисленные варианты рентгенофлуоресцентного метода отличаются кругом определяемых элементов, способами подготовки проб к анализу и способами расчета концентраций элементов. Представлен также опыт авторов по применению описанных вариантов рентгенофлуоресцентного метода в рамках комплексного исследования археологических материалов эпохи каменного века для исторической реконструкции хозяйственной деятельности населения Байкальской Сибири.

A new X-ray fluorescence technique is proposed as an alternative to the labor-consuming volumetric method for the estimation of manganese valence state in ferromanganese nodules. The approach is based on the measurement of the relative intensities of some X-ray fluorescence spectrum characteristic spectral lines and satellites (MnKβ5 and MnKβ′) preconditioned by electron transfer from the valence shell. Calibration curves were created using manganese oxide samples (MnO, Mn2O3, MnO2) and 12 certified reference materials of ferromanganese nodules, cobalt-bearing ferromanganese crusts, and manganese ores with certified (or determined by approved methods) total and tetravalent manganese content. The presence of high iron content was taken into account. A set of oceanic ferromanganese nodules samples collected in the Magellan Seamounts (Pacific Ocean) were analyzed. Differences between the results of the X-ray fluorescence method and volumetric techniques for tetravalent manganese content were 4.9 rel.%, which is comparable with the accuracy of the volumetric technique (3.6 rel.%).

Assessment of the current level and composition of dust pollution in the suburban areas of Shelekhov and Irkutsk cities was carried out based on the results of studying samples of the snow cover solid phase and snow water. The main sources of pollution in the study area are the Irkutsk aluminum smelter, including heat power engineering as well as cable and silicon production, and the Novo-Irkutskaya heat and power plant. The sampling scheme was drawn up taking into account the physical and geographical conditions, including the wind rose (mainly northwest and southeast winds), the location of industrial enterprises and the terrain. A total of 37 snow cover samples were collected in 2015, 93 in 2020 and 40 in 2021. To determine the background concentrations of elements, several samples were collected outside the study area, 15 km from pollution sources, on a territory identical to the territory of the pollution source in terms of climatic parameters, geological structure, topography, and soil cover. The place of background sampling satisfies the condition of minimum urbanization of the adjacent territory. One of the main elements of pollution from the Irkutsk aluminum smelter is fluorine, the element of the first hazard class for soils and the second hazard class for water and atmosphere. The heat and power plant is a source of Si, Al, Fe, Mg, Mn, B, as well as highly toxic volatile and soluble beryllium compounds contained in the fly ash. Under the influence of transport, road and housing construction, V, Zn, Cd, Pb, Ca, Cr, Mn, Co, Cu, C, and S accumulate. Selected elements (Al, Na, As, Li, Ni, F, Cd, Be) make it possible to determine the origin of aerosol particles and the areas of their accumulation. On the territory of the study areas, a pollution process is observed at different stages and spreads unevenly across the regions. The analysis of the spatial and temporal distribution of dust load for 2015, 2020 and 2021 according to snow geochemical monitoring data shows a downward trend in the average dust pollution for technogenically loaded suburban areas of Shelekhov and Irkutsk cities, while the formation of areas of increased dust content is saved in areas where industrial enterprises are located. The degree of pollution in some areas from 2015 to 2021 decreased from a high level to a medium degree (moderately hazardous category) according to the values of the total pollution index. The generalization of the obtained results allows us to confirm the presence of two main sources of pollution in the study area and to identify the cleanest in terms of air pollution among the territories studied.

In this study, the assessment of uncertainties introduced at different stages of the elemental analysis of archaeological ceramics has been described using the example of the Neolithic pottery sherds from Popovsky Lug (eastern Siberia). To evaluate the uncertainty introduced by sampling due to ceramic heterogeneity, three original sherds were cut into small subsamples. Powdered subsamples (250–350 mg) were analyzed using wavelength-dispersive X-ray fluorescence and inductively coupled plasma mass spectrometry methods, and the variations between analytical results for independent subsamples were compared with the variations introduced during the analytical process (measurement and sample preparation). It was shown that 250–350 mg of ceramic is sufficient to obtain good reproducibility (2–15%) between separate subsamples for most major and trace elements, even for the heterogeneous Neolithic ceramics included in this study. The differing behavior of concentration variations in some elements was explained by measuring the ceramic cross-sections by scanning electron microscopy and micro-X-ray fluorescence spectrometry, as well as by the theoretic modeling of the sampling error. The described workflow can be useful in finding uncertainties in elemental analysis results, which may affect the interpretation of bulk chemical composition in ceramic provenance studies.

A novel method for the estimation of the platinum valence state in alumina-based catalysts using the intensities of L- and M-series lines of X-ray fluorescence spectrum is proposed. The measurements of metallic platinum (Pt0) and potassium tetrachloroplatinate K2[PtCl4] (PtII) were carried out using wavelength-dispersive spectrometer. We considered the ratios of the most intense groups of closely spaced platinum X-ray fluorescence spectrum Lseries lines (L alpha 2/L alpha 1, L beta 2/L beta 1, L beta 4,6/L beta 1), as well as the broadening of PtM alpha 1,2 line as parameters influenced by the chemical bond. After decomposition using a pseudo-Voigt function, the ratio of the L alpha 1 and L alpha 2 peaks amplitudes for K2[PtCl4] was 0.118, for Pt0-0.162; the difference in the ratio of peak amplitudes in the group of L beta lines is much smaller. For the broadening of M alpha 1,2 line, the largest intensity difference (25 rel.%) between Pt0 and K2[PtCl4] was observed at 2.044 keV. Both studied analytical parameters for set of alumina-based catalysts were closer to values for Pt0 than to values of K2[PtCl4] that indicates that platinum in the studied catalysts is in a state close to metallic, probably with a slight shift towards the ionic state.

X-ray fluorescence method was proposed for a determination of major elements in samples of snow cover solid phase collected in the urban areas of the Irkutsk region near aluminum smelter and combined heat and power plant.The limitation of the analyzed sample mass, which in some cases does not exceed 50 mg, as well as the features of the elemental composition (high Al and low Si contents) require a special methodological approach to quantitative elemental analysis.Due to the lack of matrix-matched certified reference materials, the calibration set includes certified reference materials of igneous and sedimentary rocks as well as aluminum ore samples.Results of X-ray fluorescence method were compared with the results obtained by reference methods including atomic absorption, atomic emission and spectrophotometry methods.It showed that it is necessary to use samples of snow cover solid phase analyzed by reference methods as a calibration set for X-ray fluorescence analysis, which ensures the quantitative determination of major elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn and Fe).These elements are important for environmental pollution investigation.Al was discovered as a main pollutant produced by aluminum smelter, Si, Ca, Ti, Mn, and Fe -by combined heat and power plant.

An integrated approach was applied to determining the phase composition of iron ores. The data obtained by X-ray powder diffraction method, X-ray electron probe microanalysis, and physico-chemical modeling allowed us quantifying the content of the main ore (hematite, magnetite, goethite, pyrite) and some other minerals (chlorite, apatite), to assess the ratio of mineral phases and to establish polymorphic modifications of several minerals in iron ores significantly varying in phase composition. Issues related to X-ray powder diffraction limitations (limits of detection for minerals of low contents) and X-ray electron probe microanalysis (necessity of long-time measurement for methods) were solved using physical-chemical modeling required only chemical composition data that can be obtained by a routine wavelength-dispersive X-ray fluorescence method. The proposed complex of methods can be used to precisely determine the phase composition of iron ores to assess potential industrial significance.

The insufficient spectral resolution of the energy-dispersive total-reflection X-ray fluorescence (TXRF) complicates the U and Th Lα lines using for the quantitative determination of low concentrations of these elements in natural solid samples.

Long-term and continuous lake sedimentary records offer enormous potential for interpreting paleoenvironmental histories and for understanding how terrestrial environments might respond to current global warming conditions. However, sedimentary records that contain the Late Glacial and Holocene epochs are scarce in deep continental high-mountain regions. A 150 cm sediment core was obtained from Lake Kaskadnoe-1 in the East Sayan Mountains (South Siberia, Russia, 2080 m above sea level), containing a unique record of the last 13,200 calibrated years (cal yr). Chronological control was obtained by AMS 14C dating. Here, we show the first detailed X-ray fluorescence (XRF) geochemical record, with the goal of broadening our knowledge of the paleoenvironmental history of the East Sayan Mountains in the past. The determination of major compounds and trace elements (Sr, Zr) was performed from each centimeter of the Lake Kaskadnoe-1 sediment core. The inorganic geochemistry indicates significant variations in elemental composition between two major lithological units of the sediment core: the Late Glacial dense grey silty clay (150–144 cm), and the upper interval (0–143 cm) mostly consisted of dark biogenic-terrigenous silt, accumulated during the Holocene. The Late Glacial sediments accumulated 13,200–12,800 cal yr BP are characterized by high values of CIA, Mg/Al, K/Al, and Mn/Fe, and are depleted in Si/Al, Fe/Al, and Ca/Al. During the Younger Dryas cold episode, LOI enrichment was probably caused by the presence of less oxic conditions, as seen in lower Mn/Fe values, due to a longer period of lake ice-cover. The Early Holocene (12,000–7500 cal yr BP) is associated with a decreasing trend of mineral matter with fluvial transport to Lake Kaskadnoe-1 (low K/Al, Mg/Al) and stronger chemical weathering in the lake basin. The increase in Ti/Al, K/Al and CIA values over the last 7500 years suggests an increase in the terrigenous input into the lake. Low LOI values can be possibly explained by the presence of less dense vegetation cover in the basin. In summary, our data indicate that the geochemical indices and selected elemental ratios mirror the sedimentation conditions that were triggered by environmental and climate changes during the Late Glacial and Holocene.