Organic carbon in atmospheric precipitation in the urbanized territory of the South of Western Siberia, Russia

This paper presents the results of studying the contents of total (TOC) and dissolved (DOC) organic carbon in atmospheric precipitation and their deposition fluxes on the territory of the city of Barnaul. Samples of atmospheric precipitation (rain and snow) were collected from May 2016 to December 2020 in the city center, additionally at the end of winter 2018–2019 samples of snow cover were taken in the territory of the city and its environs. The studies showed a significant content of organic carbon (OC) in atmospheric precipitation: the weighted average concentrations for the study period were 7.2 ± 0.6 and 4.2 ± 0.4 mg/L for TOC and DOC, respectively. The annual flux of OC deposition with atmospheric precipitation on the territory of Barnaul over the past three years has varied within 2.4–3.9 t/km2 for TOC and 1.4–2.1 t/km2 for DOC. To visualize the spatial distribution of organic matter over the territory of Barnaul, simple kriging was used, implemented in the Geostatistical Analyst module (ArcGIS® Desktop). The flow of organic carbon input into the snow cover during the winter period was used as data for the geostatistical model. According to the model, the deposition of OC from the atmosphere occurs unevenly throughout the urban area and depends on the location and intensity of pollution sources.

Structure and magnetic properties of Bi-doped calcium aluminosilicate glass microspheres

Bi-doped CaO–Al2O3–SiO2 glass microspheres with Ca2Al2SiO7 (gehlenite) composition were prepared by combination of solid-state reaction and flame synthesis. The concentration of Bi was 0.0, 0.5, 1 and 3 mol %. The chemical composition of prepared glass microspheres was determined by X-ray fluorescence (XRF). The structural and magnetic properties of prepared glass microspheres and their polycrystalline analogues were studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscopy and SQUID magnetometry. The closer inspection of glass microspheres surface by SEM confirmed smooth surface and revealed no features indicating presence of crystalline phases. All Bi-doped microspheres are X-ray amorphous, however in case of undoped microspheres XRD detected traces of crystalline gehlenite. XRD analysis of samples crystallized at 1273 K for 10 h revealed the presence of gehlenite as the main crystalline phase. The presence of gehlenite in crystallized samples were also confirmed by Raman spectroscopy. All samples (glass microspheres and their crystalline analogues) showed diamagnetic or weak ferromagnetic behavior at room temperature, whereas paramagnetic or weak ferromagnetic behavior was observed at 2 K.

Methodological aspects of snow cover sampling for chemical analysis

At present there is a steady increase in scientific publications on studying the chemical composition of snow cover. At the same time, there are practically no modern publications on the methods of snow cover sampling for chemical analysis. The rapid development of analytical ways to determine the composition of samples in general justifies the need to improve the methodology of snow cover sampling. Today, researchers use a variety of adapted sampling methods depending on the goal, the geographic location of the study area, and the analyzed component. Each publication contains a rationale for the sampling method used. This article describes the methodology of sampling snow cover to determine its density. Methods of taking snow cover samples to determine its chemical composition most often depend on the chosen practices. The primary systematization of snow cover sampling methods has been carried out. Synthesis of literature reveals some problems, including the need for improved standardized techniques of snow sampling for chemical analysis and for the development of applied instrumentation to address snow geochemistry.

Henry’s law constants (IUPAC Recommendations 2021)

Henry’s law states that the abundance of a volatile solute dissolved in a liquid is proportional to its abundance in the gas phase. It applies at equilibrium and in the limit of infinite dilution of the solute. For historical reasons, numerous different definitions, names, and symbols are used in the literature to express the proportionality coefficient, denoted the “Henry’s law constant”. Here, a consistent set of recommendations is presented. An important distinction is made between two new recommended reciprocal quantities: “Henry’s law solubility constant” (H s) and “Henry’s law volatility constant” (H v). Eight recommended variants of H s and H v are described and relations among them presented.

Assessment of the quality of atmospheric air in woodlands of natural areas based on the intensity analysis of the process of dry deposition of impurities on an artificial underlying surface

To assess the quality of atmospheric air, the authors propose to apply the process of dry deposition of impurities on an artificial underlying surface that binds impurities in contact with it. The mass of these impurities is calculated upon laboratory exposure, after being transferred to an aqueous solution. The ease of absorber fabrication and the low cost facilitate the monitoring of air pollution at various points in woodlands, where the stationary stations for air-pollution-monitoring are very difficult and costly to arrange. A large number of control points makes it possible to identify forest areas with the highest levels of air pollution. A dynamic air-quality study at one of the monitoring points is necessary and sufficient to determine the concentration of impurities. The authors surveyed an urban forest using the proposed method, and the survey results confirmed that areas with an elevated concentration of airborne nitrogen dioxide exist within the woodland. This can lead to soil eutrophication and changes in forest biodiversity at the species and ecosystem levels.

Raman spectra of MCl-Ga2S3-GeS2 (M = Na, K, Rb) glasses

Raman spectra of (MY) x (Ga2S3)0.2−0.2x (GeS2)0.8−0.8x pseudo-ternary glassy systems (M = Na, K, Rb; Y = Cl, Br, I) were investigated systematically as a function of MY nature and alkali content. Raman spectroscopy of the Ga3S3-GeS2 glassy matrix shows a complicated local structure: corner-sharing CS- and edge-sharing ES-GeS4/2 tetrahedra, Ga-S triclusters and ETH-Ga2S6/2 ethane-like units. The Ga2S6/2 population decreases with increasing x related to a substitution of some bridging sulfur atoms around central Ga by terminal Y species with a respective decrease of the network rigidity. The formation of mixed Ga-(S,Y) environment is affected by the M+ ion size and the MY concentration.

The chemistry of melting oxynitride phosphate glasses

Oxide glasses are the most commonly studied non-crystalline materials in Science and Technology, though compositions where part of the oxygen is replaced by other anions, e.g. fluoride, sulfide or nitride, have given rise to a good number of works and several key applications, from optics to ionic conductors. Oxynitride silicate or phosphate glasses stand out among all others because of their higher chemical and mechanical stability and their research continues particularly focused onto the development of solid electrolytes. In phosphate glasses, the easiest way of introducing nitrogen is by the remelting of the parent glass under a flow of ammonia, a method that allows the homogeneous nitridation of the bulk glass and which is governed by diffusion through the liquid-gas reaction between NH3 and the PO4 chemical groupings. After nitridation, two new structural units appear, the PO3N and PO2N2 ones, where nitrogen atoms can be bonded to either two or three neighboring phosphorus, thus increasing the bonding density of the glass network and resulting in a quantitative improvement of their properties. This short review will gather all important aspects of the synthesis of oxynitride phosphate glasses with emphasis on the influence of chemical composition and structure.