Extension of the soil monitoring network via tea bag initiatives: A 3000 km latitudinal gradient in European Russia.

The increasing popularity and recognition of citizen science approaches to monitor soil health have promoted the idea to assess soil microbial decomposition based on a standard litter sample - tea bags. Although tea bag initiatives are expanding across the world, the global datasets remain biased in regard to investigating regions and biomes. This study aimed to expand the tea bag initiative to European Russia, which remains a "white spot" on the tea bag index map. We also added urban soils into the analysis, which were underestimated previously. We compared the standard and local tea brands to explore possible adaptations of the standard approach to regions with limited access to standard tea brands. The established monitoring network included natural and urban sites in six vegetation zones along a 3000 km latitudinal gradient. There was a very close linear relationship (R2 = 0.94-0.98) in the mass loss of alternative and standard tea litter. The mass loss of green tea in soil along the latitudinal gradient showed an increasing trend from north to south. Variations in the microbial decomposition of green tea were mainly explained by the latitudinal gradient, with low soil temperature identified as key factors hampering decomposition. Mass loss of the more recalcitrant rooibos tea was mainly determined via land use, with decomposition rates on average 1.3 times higher in urban soils. This pattern was in line with higher soil temperatures and pH in urban sites compared to natural counterparts. The findings of our study could prove valuable in extending the tea bag network of soil decomposition assessment into broader territories, including urban areas. Additionally, they could facilitate the involvement of citizen science and complete the database for C cycle modeling depending on climatic conditions.

Activity concentration and distribution of 40K in the soil profile of the Rostov agglomeration.

The activity concentration of 40K in soils of Rostov agglomeration was studied. Natural and anthropogenically modified soils of Rostov agglomeration were studied: Haplic Chernozems, Haplic Chernozems (Technic), Urbic Technosols. Activity concentration 40K in soils was measured by gamma-spectrometric method of radionuclide analysis. The total mass fraction of K2O was determined by X-ray fluorescence method on a Spectroscan MAKS-GV instrument. Knowing the total mass fraction of K2O, we calculated its potential radioactivity based on the fact that one gram of natural potassium has an activity concentration of 28.5 Bq. Comparison of the two methods allows estimating the involvement of 40K in biogenic cycles. No significant differences between the actual and calculated activity concentration of 40K in the soil-forming rock were revealed, while in horizons A and B the calculated activity is significantly higher. At the same time, there are no reliable differences between native and their buried analogs. The direct influence of the granulometric composition on the activity concentration of 40K was not established, but in the urban horizons with lightened granulometric composition the average activity of 40K is the lowest by reliably significant values when comparing this index with native, buried horizons and the group of heavy urban horizons. This implies that 40K is more actively involved in biogenic cycles than its stable isotopes. The burial under urban deposits is accompanied by a weak change in the activity concentration of 40K in the profile, while the difference between genetic horizons is leveled out.

[Comparison of biochemical and molecular genetic approaches for identification of environmental strains].

In order to confirm the taxonomic position of environmental strains determined based on their biochemical, cultural, andmorphological characteristics, molecular genetic identification was carried out. A number of problems in identification of microorganisms were shown to be associated with contamination of the cultures in the course of isolation. Advantages of a comprehensive approach, combining 16S rRNA gene sequencing with a set of biochemical, cultural, and morphological parameters; for identification of microorganisms isolated from environmental objects and clinical samples are discussed.

[The corrosion and electrochemical properties of new palladium-indium alloys for dentistry]. / Issledovanie korrozionno-élektrokhimicheskikh svoistv novykh palladievo-indievykh splavov dlia stomatologii.

New palladium-based dental materials were examined in a wide spectrum of pH values from 3.8 to 9.6 at 37 degrees C for 315 h. Palladium dissolves in acid (pH 3.8) media with subsequent passivation (formation of complex compounds); areas of passiveness of palladium and its alloys for other pH values were found. The potentials of passiveness currents emerging in such cases were defined for all media, and corrosion curves of the alloys plotted. A film of palladium oxide appearing on the surface of the alloy was found to prevent further corrosion. High corrosion resistance in artificial saliva and high chemical inertness of palladium-indium alloy was revealed. The mechanisms of selective corrosion of the examined alloys and passiveness currents are discussed from the viewpoint of modern physical chemistry, and experimental data are explained. Use of such alloys in dentistry is shown to hold good promise.