X-ray Fluorescence Method Research Articles

A simultaneous X-ray fluorescence and diffraction analysis method for internal depth profile probing of the volume of material

A simultaneous X-ray fluorescence (XRF) and X-ray diffraction (XRD) analysis method for probing the internal depth profile of a material using tungsten target and cadmium telluride (CdTe) detectors is presented. To select a suitable target source, a Geant4 simulation is used to simulate the characteristic X-ray photon numbers produced by metallic materials with atomic numbers ranging from 24 to 92. The fluorescence analysis demonstrates the ability to measure intensity-depth profiles to greater than 500 μm depth in CeO2 powder, at least 400 μm depth in Er2 O3 powder, at least 200 μm depth in WO3 powder and up to 500 μm depth in Bi2 O3 powder. In addition, the diffraction analysis demonstrates the capacity to measure intensity-depth profiles to a depth of greater than 5 mm in silicon powder, at least 2 mm depth in nickel powder and up to 200 μm depth in tungsten powder. This method could be extended to component and phase detection in the safety inspection of flammable and explosive materials.

Validation of Wavelength-Dispersive X-Ray Fluorescence Technique for Rapid Screening Iron and Zinc Concentration in Rice Seed

This study focuses on the validation of a wavelength dispersive X-ray fluorescence (WD-XRF) spectrometer for the rapid determination of iron (Fe) and zinc (Zn) concentrations in certified reference materials (CRMs). Five CRMs were used to establish calibration curves. The results were analyzed in terms of accuracy, precision, repeatability and linearity to assess the performance of the WD-XRF method. Accuracy was evaluated by comparing measured values to certified values, with relative accuracy calculated for each sample. Precision was determined through repeatability, where samples were measured in at least 7 replicates across different days, and relative standard deviation (RSD) was calculated. Linearity was assessed by plotting measured intensities and concentrations against certified concentrations, with the correlation coefficient (R2) values close to 1, indicating a strong linear relationship. Additionally, the WD-XRF method demonstrated high repeatability, with low RSD values across multiple measurements. The study concluded that WD-XRF is a reliable method for the rapid analysis of elemental composition, providing strong accuracy, precision and linearity for Fe and Zn determination in CRMs and can be applied as a valuable method for rapid and non-destructive analysis in various agricultural and food-related applications. HIGHLIGHTS The effectiveness of wavelength dispersive X-ray fluorescence (WD-XRF) method was evaluated to confirm its reliability for determining the elemental composition, specifically iron (Fe) and zinc (Zn), in plant-based certified reference materials (CRMs). Five CRMs were used for calibration and 2 known samples were used as the test samples to determine the analytical performance of WD-XRF. The linearity and correlation with the certified values of WD-XRF results revealed strong correlation with R-square being greater than 0.95 and the recovery percentage of 2 known samples were range from 98.75 - 109.66 for Fe and Zn concentration. WD-XRF spectrometer can be used as a rapid method for determination of Fe and Zn concentrations in rice seeds. GRAPHICAL ABSTRACT

Determination of performance properties of galvanic coatings based on cobalt

Abstract. Problem. An effective solution to the problem of the durability of construction materials is the application of protective coatings, which allow tosignificantly expand the scope of use and service life of products. The purpose of the work was to determine the performance characteristics of electrolytic coatings with Co-Ni-Zr alloy, namely adhesion and microhardness. Methodology The microhardness of the coatings was determined by the indentation depth of the diamond pyramid. Coating adhesion was determined by the fracture method. The chemical composition of the obtained coatings was determined by the X-ray fluorescence method using the SPRUT portable spectrometer. The analysis was carried out at least in 3 points with subsequent averaging of the obtained values. Electrodeposition was carried out with a unipolar current in stationary and pulsed modes (ti/tр=2/2) while varying the current density. Originality. There are no signs of delamination of the coatings on the sandpaper, which emphasizes strong adhesion to the base. The results of metallographic studies proved that Co-Ni-Zr coatings have good adhesion to the substrate material and retain it under mechanical loads. The highest value of microhardness – 850.0 MPa was obtained in the galvanostatic mode at i = = 6 A/dm2, while the zirconium content in the alloy is 1.5 wt.%. From the results of the experiments, it can be concluded that the zirconium content does not affect the microhardness of the Co-Ni-Zr coating. When the current density increases, the microhardness of the deposit decreases, which can be explained by reaching the maximum density of the deposition current. The optimal deposition current density for the galvanostatic mode is 6 A/dm2, pulsed 6 A/dm2 for obtaining coatings with high microhardness

Technological solutions to increase the level of iron extraction from stored enrichment tailings

This article presents the main results of research on the extraction of iron from the waste of the processing plant stored in the tailings dump. The average sample was classified by granulometric composition and the content of Fe2O3 was determined by the X-ray fluorescence method for each class. It follows from the results of the sieve analysis that the most iron-rich classes are +2 mm and –0.071 mm. The iron content in the +2 mm class approximately corresponds to the iron content in the source ore. When studying samples of grades +0.1–2 mm under a microscope, it was found that magnetite and hematite are bound by clay materials into floccules, which partially disintegrate upon drying. The initial material with a moisture content of 10.7% was pre-prepared for separation: a fraction of +3 mm was dried and removed. The resulting material was separated on a wet magnetic drum separator with sequential cleaning of the non-magnetic fraction in four stages with induction on the working surface of 0.18, 0.3, 0.4, 0.5 Tl. The resulting non-magnetic fraction from wet magnetic separation was separated on a dry roller separator with induction on the working surface of 1.5 Tl. The non-magnetic fraction was divided by screening into fractions: –3+2 mm, –2+1 mm, –1+0.2 mm, –0.2+0 mm. As a result of the experiment, it was found that wet magnetic separation after pre-drying makes it possible to isolate a concentrate with a content of up to 42% by weight of Fe2O3 into an industrial product. The total yield reaches 24.5% at a magnetic field strength of 0.18 Tl. Check-cleaning, as well as dry separation, do not have a significant additional effect. The conducted research and the developed technological scheme have shown the possibility of obtaining iron ore concentrate with an iron content of more than 60% from stored tailings. At the same time, the return of iron to production is 58%.

Moses Wilhelm Shapira, Hermann Weser and the Moab Expedition: Provenance Study of the Moabitica

ABSTRACT The 1870s case of the archaeological forgeries attributed to Jerusalem antiquities dealer Moses Wilhelm Shapira continues to provoke interest. This article examines the association of the Moabitica, marketed by Shapira, to their Moabite origin using the modern scientific methods of ceramic petrography and X-ray fluorescence. The results serve, in turn, to illuminate an unanswered question raised by the historical account of the German explorers’ provisional delegation to Moab. The delegation traced the sources of the Moabitica antiquities in an attempt to locate additional Moabitica in situ where they had allegedly been found. The historical account is unclear as to whether this research trip was also part of the conspiracy organised by the Jerusalem counterfeiters or whether it solely involved a workshop and a team acting east of the Dead Sea. Combining the historical narrative and the geoarchaeological analysis, the affair is examined from a perspective never before undertaken.

Inorganic Geochemistry of Coal from Patappa Village, Bone District, and Masenrengpulu Village, Barru District, South Sulawesi Province Using XRF Method

The chemical composition of coal is almost the same as that of plant tissue, containing the main elements of elements C, H, O, N, S, and P. An in-depth study of coal inorganic compounds is needed because coal inorganic compounds are the primary variable in ash formation during coal combustion. This study uses the X-ray fluorescence method to reveal the differences and similarities in inorganic chemical composition contained in coal in Bone Regency and Barru Regency. Coal in Masenrengpulu Village has the Al2O3 compound as the most dominant compound, while coal in Patappa Village has the SiO2 compound as the most prevalent compound. The concentration of inorganic sulfide minerals in the village of Masenrengpulu was influenced by igneous rock intrusion and deposition processes. In contrast, the deposition process only affected the inorganic sulfide minerals of coal in Patappa village. The significant elements found in coal in the Masenrengpulu and Patappa Villages are Si, Al, Fe, S, Ca, K, and Ti. Coal inorganic sulfide minerals in Masenrengpulu Village with Patappa Village have high concentrations in the bottom channel of the coal seam and a low concentration in the middle channel and top of the seam. Coal inorganic sulfide minerals in Masenrengpulu Village and Patappa Village have high concentrations in the coal seam's lower channel and low concentrations in the middle and upper channels. Keywords: Coal Comparison, Mallawa Formation, XRF, Inorganic Geochemistry.

Concentration of strontium and barium by co-precipitation with organic collectors and their x-ray fluorescence determination

The concentration of strontium and barium in the form of complexes with 11 organic reagents by co-precipitation with organic co-precipitants was studied for their subsequent determination by the X-ray fluorescence method. The most effective systems were those including reagents from the group of bisazo-substituted chromotropic acids—Nithchromazo and Chlorophosphonazo III. The complexes of these metals were almost quantitatively co-precipitated in the form of associates with the cations of the Brilliant Green dye when the collector was an associate of an excess of the analytical reagent with the cations of this dye. It was shown that the additional use of polyvinyl butyral as an indifferent co-precipitant allows not only the almost complete extraction of these elements from solutions but also the preparation of emitter concentrates suitable for X-ray fluorescence measurements using the background standard technique. The high efficiency allows reaching very low detection limits (IUPAC): 0.03 µg/mL for Sr and 0.19 µg/mL for Ba, even when working with small-volume samples.

Utilization of Bottom Ash from Biomass Combustion in a Thermal Power Plant to Remove Cadmium from the Aqueous Matrix.

This study provides a cost-effective method for using bottom ash from biomass combustion, which would otherwise constitute waste, to remove cadmium from acidic industrial wastewater. The X-ray powder diffraction method was used to identify the crystal forms, i.e., the arrangement of atoms in the crystal lattice, and to determine the composition of bottom ash, and the X-ray fluorescence method was used to obtain information on the elemental composition of bottom ash. The Fourier Transform Infrared method was used to analyse and identify the different functional groups occurring in bottom ash. Scanning Electron Microscopy with energy-dispersive X-ray was used to obtain detailed information on the bottom ash surface. The effect of various factors on Cd removal was studied, and optimal experimental conditions were found. The kinetic and thermodynamic equations showed that the removal of Cd2+ using bottom ash from biomass combustion was a single-layer chemical adsorption meeting the requirements of pseudo-second-order kinetics. The limiting parameter for the effective adsorption of Cd2+ using bottom ash from biomass combustion is its alkaline nature. It can only be used for solutions with pH < 2, which, on the other hand, is its advantage in practical application, namely, in the final treatment of acidic industrial wastewater.

Effects of particle sizes and roasting temperature on the Fe-Ni enrichment of limonite ore from the Wolo mine area, Southeast Sulawesi, using corncob char as reductant

Abstract The reduction roasting of a limonite ore sample from the Wolo mine area was investigated using corncob char as a reductant. The objectives of this study were to analyze the effects of particle sizes and roasting temperature on the mineralogical transformation and Fe-Ni enrichment during the roasting process. The limonite ore was prepared into three size fractions of mesh sieves (-100+150, -150+200, and -200 mesh). Limonite ore was roasted with 2g of corn cob char reductant at temperatures ranging between 800 °C and 1100 °C with a 1-hour reduction time. Limonite ore and roasted products were analyzed to determine the mineral and chemical composition using optical microscopy, X-ray diffraction (XRD), and X-ray fluorescence (XRF) methods. Results of the mineralogical analysis indicated that the sample contained chlorite, goethite, lizardite, maghemite, and quartz. Limonite ore is mainly composed of Fe2O3 (53.59%), followed by SiO2 (12.16%), MgO (2.63%), and Ni (1.52%). Results of reduced roasting of limonite ore exhibited that the ore minerals were transformed into spinel, wustite, fayalite, and some tetrataenite (FeNi). The ore with -100+150 mesh particle and heated at 1,000 °C provided the optimum enrichment of 1.74% Ni and 42.87% Fe, respectively.

Maternal hair lead and cytokine pro-inflammatory effects in preterm birth

This case-control study analyzed the lead (Pb), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α) levels in pregnant women with preterm birth (PTB) in Central Java, Indonesia. Hair samples from 72 pregnant women were collected non-invasively. The prenatal exposure to Pb was determined with the total reflection X-ray fluorescence (TXRF) method. Serum IL-6 and TNF-α were examined using enzyme-linked immunosorbent assays (ELISA). The Pb concentration in hair was slightly higher in women with PTB than those without PTB; however, this difference was not statistically significant. An elevated hair Pb level was not associated with increased PTB risk (OR 24.69, 95% CI 0.93–653.82, p&amp;gt;0.05). A serum TNF-α level ≥27 pg/ml, a serum IL-6 level ≥9 pg/ml, and the spouse’s smoking frequency were significantly associated with increased PTB risk (TNF-α OR 42.25, 95% CI 5.26–339.61; IL-6 OR 22.33, 95% CI 3.12–158.54; spouse’s smoking frequency OR 1.28, 95% CI 1.09–1.5), while the maternal hemoglobin concentration significantly decreased PTB risk (OR 0.43, 95% CI 0.2–0.927). This study demonstrates that maternal hair Pb concentration has no significant relationship with PTB. Serum TNF-α, IL-6, and the spouse’s smoking frequency potentially increased PTB risk, while the maternal hemoglobin level is a protective factor.

Gabbro of the mantle part of the ophiolite section in the Alapaevsky dunite-harzburgite-gabbro massif (Eastern zone of the Middle Urals)

Research subject. An intrusive body of gabbroids breaking through mantle peridotites (dunites and harzburgites) of the Alapaevsky ophiolite massif (Eastern zone of the Middle Urals). Methods. The contents of petrogenic elements were determined by the X-ray fluorescence method; the contents of rare and scattered elements were studied by the ICP-MS method. The age of gabbroids was determined by 147Sm-143Nd ID-TIMS by isotope dating. Results. The gabbro and their containing ultramafic rocks were established to be of almost the same age of about 580 Ма, which indicates their belonging to a single ophiolite association of the Vendian age. At the same time, the gabbroids of the Alapaevsky massif differ sharply from both isotropic and stratified gabbro of the crustal part of the ophiolite section, fragments of which are observed within the Eastern zone of the Middle Urals, in terms of a significantly reduced content of light REE, rare alkalis, barium, uranium and thorium, as well as the absence of Pb maxima on spider diagrams. Conclusions. The established features in the composition and intrusive occurrence of the gabbro of the Alapaevsky massif among mantle ultramafic rocks indicate that the studied rocks cannot be identified with gabbroids of the crustal part of the ophiolite association. This suggests that this rather large intrusion of gabbro may be analogous to small veins and dikes of gabbroids observed among mantle peridotites in a number of ophiolite massifs, such as Voikar-Synyinsky massif in the Polar Urals and the Samail ophiolite in Oman. The distribution specifics of rare elements on the spider diagrams of the gabbroids of the Alapaevsky massif, i.e., the presence of Sr and Ba maxima and Nd and Th minima, as well as the Harzburgite composition of the mantle restite containing the gabbro body under consideration, indicate that the Vendian ophiolite association of the Eastern zone of the Middle Urals formed in a suprasubduction (pre-arc) environment. A model for the formation of large masses of gabbro in the mantle part of the ophiolite section is proposed.

Ion-exchange of copper into mordenite and clinoptilolite zeolites by molecular dynamics simulations and experimental investigations

Copper-exchanged zeolites have been subjected to several investigations because of their application as selective redox-active catalysts, and sensors. However, the ability of different types of zeolites to exchange Cu ions remains a matter of debate. All-atom molecular dynamics (MD) simulations, energy dispersive X-ray spectroscopy (EDS), and X-ray Fluorescence (XRF) methods have been used to evaluate the exchange of Cu(II) in mordenite and clinoptilolite zeolites using an aqueous method in the current study. Several parameters of copper ions have been measured for both types of zeolites, such as ion exchange ratio, mean square displacement (MSD), diffusion coefficient, and radial distribution function (RDF). These parameters were calculated for each zeolite system at different Cu ion concentrations in the feed solution. Copper exchange ratio and RDF analyses revealed a higher exchange ratio of copper ions in the mordenite framework. Analysis of the potential energy indicates the major adsorption sites for mordenite and clinoptilolite, which are located in the largest cavities of the zeolites. The adsorption energy of the mordenite sites (1.52 eV) was larger than that of clinoptilolite (1.28 eV). The stronger attraction between the copper ions and mordenite sites is consistent with the lower diffusion coefficients of the ions in this zeolite. The ion-exchange abilities of the zeolites were examined using EDS analysis. According to the EDS results, the mordenite zeolite exchanged more copper ions than the clinoptilolite, which is in agreement with the computational results.

Energy Dispersive X-Ray Fluorescence Spectrometry Using a Matrix Corrected Fundamental Parameters Algorithm vs. Acid Digestion with ICP-AES: A Comparison of Two Methods for Soil Elemental Analysis

ABSTRACT Energy dispersive X-ray fluorescence spectrometry (ED-XRF) is evaluated as an alternative to conventional acid-mediated soil digestion methods for analysis of aluminum (Al), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), silicon (Si), strontium (Sr), titanium (Ti), and zirconium (Zr). The Kellogg Soil Survey Laboratory (KSSL) currently uses microwave-assisted digestion with inductively coupled plasma – atomic emission spectrometry (ICP-AES) to measure the 12 elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Sr, Ti, Zr). The equipment needed to conduct the digestion method is expensive, the materials are hazardous, and the method is laborious. The Kellogg Soil Survey Laboratory (KSSL) has observed variable elemental recoveries for certain elements. The objective of the study was to evaluate an ED-XRF method as an alternative to the KSSL digestion method. The literature offers few examples of X-ray fluorescence (XRF) method development and validation. The candidate ED-XRF method offered a more efficient, less expensive, and less hazardous approach for measuring the 12 elements. Relative to the digestion method, the candidate ED-XRF method showed improved precision and accuracy for specific elements.

Portable X-ray fluorescence of zinc and selenium with nail clippings-Mother and Infant Nutrition Investigation (MINI).

Zinc and selenium are essential minerals for human nutrition. Reliable biomarkers of zinc status and selenium status in humans are therefore important. This work investigates a novel portable X-ray fluorescence (XRF) method with the ability to rapidly assess zinc and selenium in nail clippings. This approach used a mono-energetic X-ray beam to excite characteristic X-rays from the clippings. Nail clippings were obtained from the Mother and Infant Nutrition Investigation (MINI), a study designed to assess nutrition in a population of women and their breastfed children in New Zealand. Twenty mother-infant pairings were selected to provide nail clippings at two time points (visit 1 at 3 months postpartum; visit 2 at 6 months postpartum). Nail clippings from each mother-infant pairing were divided into three groupings of clippings prior to analysis: those obtained from a big toe of the mother, those from the other toes of the mother, and those from the toes and fingers of the infant. Clippings were prepared and mounted prior to XRF measurement, providing four distinct fragments from each clipping grouping. These fragments were assessed by XRF using a measurement time of either 300 s (visit 1) or 180 s (visit 2). XRF results were determined through both an automated system output and an analysis of the X-ray energy spectrum. Following this assessment of zinc and selenium with the non-destructive XRF method, clippings were measured for zinc and selenium concentration using a "gold standard" technique of inductively coupled plasma mass spectrometry (ICP-MS). Mean ICP-MS concentrations ranged from 122 μg/g to 127 μg/g for zinc, and from 0.646 μg/g to 0.659 μg/g for selenium. Precision, assessed by a relative standard deviation of measurement, was superior for ICP-MS relative to XRF. For both zinc and selenium, XRF results were compared with ICP-MS concentrations. Linear equations of best fit were determined for each comparison between XRF and ICP-MS results. Coefficients of determination (r2) were stronger for zinc (from 0.74 to 0.95) than selenium (from 0.53 to 0.70). A decrease in XRF measurement time from 300 s to 180 s did not appear to adversely affect the correlation between XRF and ICP-MS results. Using the mono-energetic portable XRF method, the correlation of XRF zinc results with ICP-MS zinc concentrations was improved over previous findings, and selenium measurement was reported for the first time. The method may prove useful for future applications to trace element analysis using nail clippings as a biomarker.

Novel application of the X-ray fluorescence method for the determination of FeO content for reference materials characterization

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.

Clay mineralogy in mylonite weathering products from Njimom (west Cameroon): origin and terracotta suitability

This study investigated the mineralogical assemblage of weathering products developed on mylonite rocks in west Cameroon. Smectite and vermiculite occurrence was studied, particularly to emphasize its origin and the potential of the samples in terracotta production. Samples characteristics were determined through X-Ray Diffraction (XRD) and X-ray Fluorescence (XRF) methods. Weathering products were observed along road trenches of 450 m long and 50 m height on a syenitic basement rock intruded by magmatic rock veins. Clay minerals are mainly composed of kaolinite and illite. 2:1 swelling clay minerals (vermiculite, montmorillonite) occur in some samples mainly originated from the contact between weathering materials and quartzo feldspatic bands. The main oxides are SiO2 (46–72%), Al2O3 (16–31%), Fe2O3 (2–16%) and K2O (0.1–6%). Vermiculite may be formed by fluid-mineral interactions during alteration of the chlorite in the plasmic microsystems of the soil. Structural changes in the upper part of the saprolite leading to the transformation of vermiculite into smectite under supergene alteration control, which predominates in humid tropical zones. Heavy rainfall leads to the formation of kaolinite at the expense of 2:1 clay minerals. Empirical classification revealed that the studied weathering products can be used to produce common bricks.

Using optimized monochromatic energy dispersive X-ray fluorescence to determine the cadmium concentration in cacao and soil samples

Following the implementation of food safety limits on cadmium (Cd) in cacao products, there has been a growing demand for monitoring Cd in cacao tissues and soils. Traditional methods like acid digestion followed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) are time-consuming and costly. X-ray Fluorescence is an alternative technique that offers advantages in terms of speed, cost, ease of use and less environmental impact. However, to date, relatively high detection limits have impeded its application for food safety limits. This study examines a Monochromatic Energy Dispersive X-ray Fluorescence (MEDXRF) method optimized for Cd analysis as an alternative to ICP-MS. Using a measurement time of 200 s, the average limit of quantification (LOQ) was 0.178 mg Cd kg−1 for biological samples and 0.205 mg Cd kg−1 for soil samples. A strong correlation (y = 1.013 x + 0.003, R2 = 0.984) with ICP-MS results was found for 95 bean, 16 cacao liquor, 75 leaf, and 91 soil samples. The coefficient of variation (CV) among three replicates was below the threshold value of 15 % for most samples with Cd concentrations above the reported LOQ values. Additionally, a significant difference in CV was obtained between soils sieved over 500 μm (median 8.2 %) or 2 mm (median 9.8 %). However, no significant difference in CV was observed between 500 μm unpeeled beans and cocoa liquor with particle size of 20 μm. Based on our data, the proposed procedure is to analyze three replicates for 200 s with a sample size of 500 μm. The optimized MEDXRF technique offers important advantages in terms of cost-effectiveness and efficiency of routine Cd monitoring in the cacao supply chain, large-scale screening, and scientific research, and could be extended to other crops and heavy metals that are subject to food safety regulation at low concentrations.

Ecological and geochemical assessment of soils in residential areas of Eastern Transbaikalia

Relevance. Environmental pollution by mining wastes is one of the most urgent environmental problems. Aim. To determine the degree of soil pollution in the residential areas of Eastern Transbaikalia. Objects. Total soil pollution according to the Saet formula (Zc) was studied in 30 settlements of Eastern Transbaikalia, including 14 settlements related to mining. Methods. In order to determine the degree of soil contamination, the settlements were grouped: settlements at gold ore, molybdenum lead-zinc and rare-metal deposits, as well as settlements not related to mining. The factual material was obtained during the research under the basic projects of the Institute of Natural Resources, Ecology and Cryology of the Siberian Branch of the Russian Academy of Sciences from 2000 to 2022. In addition, published data and materials of the territorial geological funds (Chita) were used. The X-ray fluorescence method was used to determine the concentrations of chemical elements in analytical laboratories of the Geological Institute of SB RAS (Ulan-Ude), ISP-MS of ZAO "SGS Vostok Limited" (Chita). Results. Among the considered groups of settlements the following indicators of total soil contamination degree (Zc) were established: mining settlements of lead-zinc deposits – 68.87; gold deposits – 30.67; molybdenum deposits – 32.25; rare-metal deposits – 0.03; settlements not related to mining activity – 0.32. According to the total degree of soil contamination Zс, the settlements of lead-zinc deposits correspond to extremely hazardous, molybdenum deposits – hazardous; gold deposits – moderately hazardous; the settlements of rare-metal deposits and the ones not related to mining activities – low levels of pollution.

High-resolution chemofacies and pore system characterization of the Pennsylvanian Cline Shale, Midland Basin, Texas

The connections between the depositional environment, sediment chemistry, and pore structure of deep-water mudstones are still not completely understood. This study: 1) investigates the sediment chemistry and the depositional conditions of the Pennsylvanian Cline Shale chemofacies in the center of the Midland Basin, 2) characterizes the conditions favorable to organic matter accumulation of each mudstone chemofacies, and 3) examines the connection between the pore structure and the mudstones’ paleo-environmental and paleo-geochemical context and processes. This study uses X-ray fluorescence (XRF) and statistical methods (Isolation Forest, Principal Component Analysis, and K-means) to identify four chemofacies of 127 m of Cline Shale core from the Matthew 'D' 0906 well located in the Midland Basin depocenter in Glasscock County, Texas. In addition, petrographic and scanning electron microscopy and measurements by dual-energy computed tomography, X-ray diffraction, Rock-Eval pyrolysis, N2 isothermal adsorption tests, and mudrock reservoir properties were conducted on thin-sections, core slabs, and samples to understand the bulk geochemistry and petrophysical properties of the mudstones. Four chemofacies are identified: (1) Siliceous Mudstone with high Zr and low Ca and P, (2) Calcareous-argillaceous Mudstone I with high Ca and Zr, and low P, (3) Argillaceous Mudstone with high P and low Ca and Zr, and (4) Calcareous-argillaceous Mudstone II with high Ca and P, and low Zr. Based on elemental distribution, the first two and last two chemofacies are interpreted as low sea-level deposits and high sea-level deposits, respectively. Water stratification and P regeneration accounted for the highest total organic carbon (TOC) content, which resulted in the high porosity and pore volume of the low sea-level Siliceous Mudstone chemofacies, especially visible in the 8 nm–186 nm organic matter pores. Carbonate input hinders the development of the inorganic pore system, especially for organic lean Calcareous-argillaceous Mudstones. Nine sea-level cycles were observed in the cores and correlated to nine US mid-continent cycles attributed to the 405-kyr Milankovitch parameter (long orbital eccentricity) during the late Pennsylvanian. We hypothesize that late Pennsylvanian climate change, paced by orbital cycles, controlled the distribution and stacking pattern of mudstone chemofacies, which also controlled source rock quality and consequent pore system development.

Development of cement slurries with additives of nanoclay particles for the construction of oil wells at elevated temperatures

Relevance. Strength decrease is a phenomenon that becomes more pronounced as the temperature rises above 110°C. It is characterized by significant chemical and microstructural changes that Portland cement undergoes at high temperatures. Adding silica particles (SiO2) to cement can significantly increase cement resistance to strength reduction when the temperature exceeds 110°C. Nanoclays are currently used in the cement industry to increase the strength of the cement matrix due to their ability to fill capillary micropores and due to their relatively small particle size. Aim. To investigate the effect of adding nanoparticles (nanoclay) to Saudi grade G cement on compressive and tensile strength, and cement stone permeability under high temperature conditions (300°С). Objects. Six samples of cement mortars with different concentrations of nanoclay, cement stones from, tested after 7 and 28 days of hardening at 25 and 300°C. Methods. Cement chemical composition was evaluated by the X-ray fluorescence method with the WORKSTN-V Olympus Vanta X-ray fluorescence analyzer. Cement physical composition was evaluated by the method of ray diffraction on the Mastersizer 2000 laser particle size analyzer. The test of the grouting stone samples was carried out in accordance with ISO 10426-2:2003 on a hydraulic press 65-L1132. The tensile strength of the samples by the Brazilian method was tested in accordance with ASTM D 3967-08 standard on a hydraulic press 65-L1132. The permeability of the samples was determined by single-phase stationary filtration at a facility for studying the filtration and capacitance properties of the PIK-OFP-UCH core in accordance with ISO 10426-2:2003. Results. The data obtained showed that cement destruction at extremely high temperatures can be avoided by using nanoclay (up to 3% by weight of cement). The microstructure of the cement matrix was significantly affected due to the aggregation of nanoparticles when more than 3% of nanoclay was added. All rheological characteristics of the cement slurry were improved by the addition of nanoclay particles.