Spatiotemporal Analysis of Multi-Year Wildfires and Emissions of Trace Gases and Aerosols in Russia Based on Satellite Data

Izvestiya, Atmospheric and Oceanic Physics - An analysis is performed of the annual and intraseasonal dynamics of wildfire areas and volumes of trace gas components (CO, CO2, CH4, NO, and NO2) and...     

Study of Thermal Fields before Strong Earthquakes in Turkey on March 8, 2010 (M = 6.1), and January 24, 2020 (M = 6.7)

Izvestiya, Atmospheric and Oceanic Physics - Thermal-field anomalies recorded during the preparation and occurrence of strong earthquakes on March 8, 2010 (M = 6.1), and January 24, 2020 (M = 6.7),...     

Mineralogical-technological peculiarities of the ores of the Skrytoe Scheelite deposit and prospects for their dressing

This work presents the results of the study of a small technological sample taken from the borehole core drilled in the ore body of the Skrytoe deposit. Data on the mineral composition and the textural-structural features of the ores are reported. It was found that the studied ores are characterized by low concentrations of tungsten (WO₃ less than 0.5%), high contents of phosphorus (P₂O₅ > 0.5%), and a content of sulfide minerals of no more than 10%. Based on these results, it was proposed to modify the available dressing scheme developed by the ZAO Mekhanobr-Inzhiniring company. This will permit one to optimize the efficiency of the scheelite extraction during mining.     

A Study from Space of Anomalous Variations of Various Geophysical Fields during the Preparation of a Series of Strong Earthquakes in Italy in 2016–2017

Izvestiya, Atmospheric and Oceanic Physics - A time series of the occurrence of thermal anomalies, aerosol optical-depth anomalies, and total electron content of the ionosphere during the...     

Dualistic distribution coefficients of trace elements in the system mineral–hydrothermal solution. IV. Platinum and silver in pyrite

The FeS₂–Ag–Pt–As system was studied using hydrothermal thermogradient synthesis (with internal sampling) of pyrite crystals at a temperature of 500°C and pressure of 1 kbar in ammonium chloridebased solutions. The modes of occurrence of precious metals (PM) were determined using atomic absorption spectrometry (AAS) in its version of statistical selections of analytical data on single crystals (SSADSC), electron microprobe analysis (EMPA), scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The concentration of Pt in its structural mode in pyrite is as high as 10–11 ppm and is practically not correlated with the As concentration. The dualistic distribution coefficient of Pt between pyrite and hydrothermal solution is 21 ± 7 for the structural mode and 210 ± 80 for the surface-related mode of this element. No inclusions of either any Pt-bearing minerals or Pt itself was detected. Platinum is an element highly compatible with hydrothermal pyrite and is different in this sense from gold, and pyrite is underestimated as a potential concentrator of platinumgroup elements (PGE). The distribution of Ag in pyrite is highly heterogeneous. The likely reason for this is that the Ag solid solution cannot be quenched, and hence, the Ag concentrations broadly vary and are very unsystematically distributed in natural pyrite crystals. Assuming this hypothesis, the limit for Ag accommodation in FeS₂ can be estimated using SSADSC at 0.09 ± 0.06 wt % under the experimental parameters, and the distribution coefficient of the structural Ag mode is thereby evaluated at 1400 ± 700. When crystallizing together with FeS₂ proustite (Ag₃AsS₃) near its melting point, forms mixtures with dervillite (Ag₂AsS₂), in which Ag deficit is counterbalanced by excess divalent As. The limit of As incorporation into pyrite under these conditions is ≤0.1 wt %. SEM-EDS and XPS data indicate that the surface phases are of three types. In the course of crystal growth, practically two-dimensional nonautonomous phases (NP) are aggregated into submicroscopic and micrometer-sized crystalline bodies (mesocrystals) that largely inherit their unusual minor-element composition from NP and are enriched in Ag, Pt, As, and other minor elements. NP and mesocrystals are enriched in Al, which was transferred into them from the Al-bearing Ti alloy of the reaction containers. Silver occur in the volume of the crystals and on their surface as monovalent silver sulfide. Arsenic was detected mostly in the form of di- and trivalent arsenic sulfides. Pentavalent arsenic oxide was identified only on the surface of the crystals and can be easily eliminated by ion milling.