It was found that salt efflorescence gradually develops on the surfaces of pellets pressed from marine sediments after analysis by X-ray fluorescence spectrometry when the pellets remain exposed to laboratory air during the summer–autumn period. Chemical characterization identifies the efflorescence as sodium chloride. In some cases, the intensity of the chlorine Kα line increases by a factor of up to 10 relative to its initial value, and the sodium Kα line exhibits a comparable increase. In contrast, the intensities of the X-ray fluorescence lines from the other major elements in the sample in some cases decrease more than twofold. Grinding the pellets followed by back pressing restored the analytical results to their initial values. We evaluates factors that promote sodium chloride migration to the pellet surface, including fluctuations in air humidity and temperature in the storage room, as well as the residual moisture content of the sample or of the binder during the pellet preparation. This behavior arises from the high NaCl content of marine sediments, although similar processes may also occur at lower sodium chloride concentrations.

The main problem in determining chlorine in marine sediments is the lack of a sufficient number of reference materials (RMs) with certified values for the content of this element. In the RMs of the earlier SDO series (bottom sediment standards) and the newer OOPE series (pelagic sediment standards), chlorine contents in clays and silts are given only as informative values. A method for the X-ray fluorescence determination of chlorine in RMs of pelagic sedimentary deposits (clays and silts) of the SDO and OOPE series is proposed. The emitters were prepared by pressing the test material—previously thoroughly homogenized and dried at 105°C—with the addition of polystyrene as a binder. Calibration characteristics for chlorine determination were obtained using reference samples, the matrices of which were RM clay and silt samples washed free of chlorine, with calculated portions of NaCl powder added. The results of chlorine determination in the original clay and silt standards agree well with the informative values given in the RM certificates. The uncertainty of chlorine determination by the X-ray fluorescence method in clay and silt RMs within the concentration range of 2–4

The Laptev Sea belongs to the polar climate region, characterized by minimal influence on geochemical weathering processes. The dominant role in the formation of sedimentary rocks in high latitudes is played by mechanical sorting of sedimentary material. Using 15 sediment cores located along 120°‒130° E from the Lena Delta to the continental slope and in the Sadko Trough as an example, a close relationship between the grain-size and geochemical composition of marine sediments was revealed. The results of the study showed that shelf sedimentation occurs in at least two stages: (i) accumulation of sediments in coastal area, the area directly adjacent to the sources of sediments, and (ii) the subsequent mechanical sorting of sedimentary material on the shelf itself. At the first stage, the finest clay fraction is partially separated from the primary terrestrial sedimentary material. At the second stage, as one move away from the coastal area, the sand and silt fractions are separated. This sedimentation pattern is determined by the combination of the Lena Delta morphology and the Siberian Coastal Current. In conditions of an unstable hydrodynamic regime of the shallow shelf, predominantly sandy sediments (SiO2/Al2O3 > 4.5) accumulate at a rate of <0.5 g cm‒2 yr‒1. These sediments differ from the sediments of the terrestrial area by a higher content of Si and a lower content of Ti, Mg, Fe and Ni. In conditions of a calm hydrodynamic environment of the Sadko Trough, predominantly silty sediments (SiO2/Al2O3 < 4.5) accumulate at a rate of >0.5 g cm‒2 yr‒1, characterized by a higher content of Ti, Mg, Fe and Ni and a lower content of Si. The contents of K, Rb, Cr and Ca in shelf sediments do not show a clear correlation with grain-size distribution and are thus not informative for reconstructing sedimentation patterns.

The main fluorine-concentrating minerals in rocks are mainly apatites, amphiboles, micas, fluorites, sphenes, villiomites, in which fluorine is found in compounds with Ca, Mg, Na. The yield of the X‑ray fluorescence of fluorine depends on the element with which it is chemically bound. Taking into account this factor, three versions of calibration dependences for fluorine in the composition of CaF2, MgF2, and NaF were obtained using pressed tablets. Mixtures of these fluorides with granite, basalt, and limestone were used for calibration. To select an adequate calibration for the determination of fluorine in a batch of unknown samples, it was proposed to use the results of a selective analysis of fused samples of the batch

It is shown by inductively coupled plasma atomic emission spectroscopy that elements (Fe, Mn, Cu, Cr, Co, and Ni) are strongly retained in the hydrogel (HG) phase and are virtually not desorbed. A method is developed for the determination of metal ions based on the sorption preconcentration of elements by polymer hydrogels and the subsequent direct analysis of the sorbent by X-ray fluorescence (XRF) spectrometry. It is shown that, to determine the concentrations of elements in the HG after sorption, XRF spectrometry can be used directly on the solid phase, excluding the stage of the desorption and additional sample preparation. The calibration curves are linear in the range 0.05–1.3 μg/mL. The limits of detection for metals in the solid phase are 0.0002, 0.0003, 0.0002, and 0.0005 wt % for Fe(III), Cr(VI), Cu(II), and Mn(II) ions, which corresponds to the concentrations of these elements in the initial solution 0.007, 0.017, 0.007, and 0.010 μg/mL. The relative standard deviations are 4.1, 3.2, 4.1, and 5.2%, respectively. The method was tested in the determination of Cr(VI), Mn(II), and Cu(II) in tap water.

The peculiarities of the composition and internal structure of chondrite NWA 12370, petrological type H5 S1 W1, were studied by means of Raman spectroscopy, XRF, and electronic sounding. The dependence of the mechanical properties of chondrite on the external hydrostatic pressure was studied by means of ultrasonic waves and static methods. This meteorite is a fragment of stone rain from the debris of the inner part of a large asteroid, about 200 km in size. We compared the mechanical characteristics obtained with those of the well-studied Pultusk chondrite of the same type, impact breccia H4/H5 S2 W1. At the early stage of the Solar System, such planetesimals made a significant contribution to the geochemical evolution of the terrestrial planets. Therefore, understanding the peculiarities of the relationship between the H chondrite’s internal structure and elastic properties is essential for assessing their contribution to the crust and upper mantle composition of the Earth and Moon and clarifying the conditions for the formation of the redox potential of the planetary interior.

Specific features of the excitation of the X-ray fluorescence of fluorine in the presence of petrogenic elements are studied experimentally. The dependence of the intensity of the FKα-line on the atomic number of macroelements entering the composition of rocks is studied. It is found that the major contribution to the intensity of the FKα-line due to the effect of selective excitation is made by sodium fluorescence. The dependence of the intensity of the FKα-line on elements with atomic numbers 11 < Z ≤ 26 exhibits a maximum in the region Z ≈ 20–22. This is due to the contribution of photo and Auger electrons of the listed elements. The obtained experimental data indicate that the yield of X-ray fluorescence of fluorine depends on the compound containing fluorine. The optimum operation mode of the X-ray tube was chosen for the determination of the FKα-line.

Исследованы некоторые особенности валентной линии FeLα1,2: показана связь между интенсивностью линии и степенью окисления железа, установлена зависимость интенсивности линии FeLα1,2 от присутствия в пробе других элементов.

A method was developed for the quantitative estimation of the content of trapped melt in various dunite types and the composition of this melt on the basis of the major- and trace-element characteristics of the dunites and compositions of their chrome spinels. Our approach is advantageous over the method based on clinopyroxene geochemistry and clinopyroxene–melt partition coefficients for the contents of the light REE and more incompatible elements in melt, comparable with it for the middle REE, and possibly less accurate for the heavy REE and Sr. The estimated mean contents of trapped melt in dunites from ophiolite and concentrically zoned complexes are 1.0–1.5 wt %, which is probably typical of various dunite types, including cumulate dunites from layered complexes. These values are an order of magnitude higher than previous estimates. The correspondence between the compositions of calculated trapped melts in dunites and real natural melts indicates that the estimated contents of trapped melt in dunites are realistic, and the mineral–melt partition coefficients that were used in our calculations are valid for the complexes considered in this paper. In general, the proposed method is suitable for serpentinized dunites, including dunitic serpentinites.

In this paper, we report new data on the lithological and chemical compositions of the surface layer (0–2 cm) of bottom sediments from various zone of the Kara Sea: the estuaries of the Ob and Yenisei rivers, open part of the shelf, Eastern Novaya Zemlya Trough, Voronin Trough, and Novaya Zemlya bays. The sediments were collected during five cruises of the R/V Akademik Boris Petrov (2000, 2001, and 2003) and the R/V Akademik Mstislav Keldysh (2015 and 2016). Based on the statistical analysis of the obtained data array, all the bottom sediments were divided into cluster groups comprising their lithological and geochemical types. The obtained clusters and REE + Y systematics were used to distinguish facies genetic types of the bottom sediments and determine the accumulation zones of Holocene sequences. They are bounded by river estuaries, a shallow marine zone adjoining the southeastern coast of the sea, and deep troughs. The main sources of Holocene sediments in the Kara Sea are the suspended particulate materials of the Ob and Yenisei and materials transported by glacial meltwater from the Novaya Zemlya and Severnaya Zemlya archipelagoes. The dispersion of fine suspensions is controlled by the circulation of surface sea currents. The accumulation of suspended materials on the bottom is complicated by wave effects and circulation of bottom sea currents, which remove fine sediment fractions from the shallow regions of the sea and transport them into the deepest hydrodynamically calm parts of troughs.

In view of ecological problems stemming from the leakage of reservoirs with liquid radioactive wastes (LRW) and groundwater contamination with radioactive Cs+ and Sr2+, we have estimated the physicochemical (including sorption) characteristics of clinoptilolite-bearing tuff (CBT) from the Chankanai deposit in Kazakhstan. Data were obtained on the chemical and phase composition of CBT, its total cationexchange capacity, and equilibrium (exchange isotherms) and kinetic (diffusion coefficients) characteristics in sorbing radioactive Cs+ and Sr2+ from 0.07 n CaCl2 solution (model solutions of groundwaters). We proved that CBT efficiently sorbs Cs from this solution and practically does not sorb Sr and elucidated the reasons for the low selectivity with respect to Sr2+. Based on the equilibrium and kinetic characteristics of the process, a mathematical model is suggested for Cs sorption under dynamic conditions. The protection lifetime of the clinoptilolite-based geochemical barrier is evaluated.