Microbial Interactions Drive Distinct Taxonomic and Potential Metabolic Responses to Habitats in Karst Cave Ecosystem

In general, the constant physicochemical conditions and limited nutrient sources over long periods in the subsurface support a stable ecosystem in karst cave. Previous studies on cave microbial ecology were mostly focused on community composition, diversity, and the relationship with local environmental factors.

Composition and abundance of weed-species in relation to physicochemical variables in soil for peach Prunus persica L. var. Rubidoux

Weeds are the main biological constraint for production and sustainability in agricultural systems. This is due to the ability of weeds to modify soil physicochemical conditions (i.e., nutrients, pH, organic matter). It is for this reason that having information on the physicochemical characteristics of the soil within the crop allows observing ecological aspects and the distribution of weed species. The objective of this study was to determine the composition and frequency of weed species and their relationship with soil physicochemical variables in peach Prunus persica L. var. Rubidoux. This study determined the composition and frequency of weed species in relation to physicochemical variables in soil for apeach crop with a total of twenty 10×10 m quadrats within a 2 ha peach crop. Weed species were identified taxonomically. A physicochemical characterization of the soil was performed in each quadrat. A total of 13 weed species were recorded, distributed in 10 families and 8 orders, with the Asteraceae family being the most representative. Additionally, physicochemical variations were found in the soil samples in the peach crop. The soil data were contrasted with the distribution patterns and frequency of weed species. Some weed species were not individually related to the soil physicochemical variables. Our results support efforts to explore how variations in soil physicochemical conditions in a crop can modulate weed species distribution patterns.

Золотая минерализация штокового рудного поля (Магаданская область)

The authors briefly characterize the geology and structure of the Shtokovoye ore field attached to the area where the Khurchan-Orotukan zone of tectonic-magmatic activation overlays the structures of the Yana-Kolyma ore-bearing belt. Studied are mineral associations and physicochemical conditions of gold ore bodies, located both in granites and in hornfelsed sedimentary masses. By the main features of its geological structure, ore composition, and physicochemical formation conditions, the Shtokovoye ore field mineralization corresponds to the "depth" group of the gold-rare-metal formation, analogous to the Butarnoye, Basugunyinskiye, Dubach, and Nadezhda occurrences. Its ores are peculiar in the late epithermal mineralization, which is associated with the Okhotsk-Chukotka volcanic belt and overlays the sinaccretional gold-rare-metal mineralization.

CONTACT CLARIFIERS IN THE PREPARATION OF DRINKING WATER

The article discusses the problem of improving the technological process of clarifying water for drinking purposes using contact clarifiers, which allows to reduce the consumption of reagents, improve water quality, reduce capital and operating costs, and reduce the cost of water. The method of water treatment, based on the use of the phenomenon of contact coagulation, is called the method of contact clarification. This method is able to provide a high and stable effect under various physicochemical conditions of coagulation, changing according to the seasons of the year with lower doses of coagulant than in the usual scheme of water treatment with sedimentation and filtration. It was found that the contact coagulation of suspended and colloidal impurities of water on sand grains when water moves through granular filters is faster, more complete, more stable when the physicochemical conditions of coagulation change according to the seasons of the year. And, finally, at lower doses of coagulant than the usual coagulation of these impurities in the free volume of water in flocculation chambers and settling tanks. It is advisable to use contact clarifier in one-stage treatment schemes for low-turbid colored waters, when the total content of suspended solids in the water supplied to the contact clarifiers, including the suspension that is formed as a result of the introduction of reagents into the water, does not exceed 150 mg/dm3. With a higher suspension content in water, the water consumption for flushing contact clarifiers increases sharply. It was found that the zones of contact coagulation when using a conventional coagulant solution are slightly smaller than when treating water with a modified solution of aluminum sulfate (the latter takes place on the curves of contact coagulation of both low-turbid and turbid waters). The analysis of contact coagulation zones shows that when treating water using a modified coagulant solution, it makes it possible to reduce the calculated doses of coagulant by an average of 30-45% without deteriorating the quality of water clarification.