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The endangered endemic species Sevan trout (Salmo ischchan Kessler, 1877) is under the threat of extinction and its survival is dependent on restocking by smolts. Thus, there is an urgent need to find an effective solution for restocking wild populations. After developing a theoretical methodology to reveal the most suitable parts of spawning rivers for natural reproduction, we consider the incubation of eggs in the wild as an appropriate method for the validation of the results of the theoretical assessment. Thus, we estimate the eggs’ survival differences in the wild and microcosm conditions which found significant differences in the sac-fry emergence rate in the zones assessed as “partly suitable” and “unsuitable”. Also, the results show that the emergence of eggs in the wild was less than in the microcosm conditions and the success rate of emergence of eyed eggs in the wild was higher than that of the green eggs. The results of one-way ANOVA, correlation and general linear mixed model analyses have in general proven the theoretical assessment but raise some questions on the completeness of using a set of abiotic criteria as the range of success during different experiments varies significantly. Full article

The article presents the results of the seven-year study on the state of arable lands and wastewaters in the districts of mining enterprises in Armenia. An assessment of the ecological and toxicological state of wastewaters and contaminated areas was carried out. Methods for their purification are proposed aimed at their further use and obtainment of environmentally safe agricultural products. An area of about 0.5 ha, next to the rural community of Syunik in southern Armenia, has been polluted for many years by mining sludges from the nearest mine watertight cofferdam of the Zangezur copper-molybdenum combine. Activities have been carried out to clean up the soil in this area. After plowing, soil improvers (zeolite, bentonite, and manure) were introduced into the soil. On-site treatments, soil tillage, and the introduction of soil improvers into the soil was implemented in late autumn. Soil and plant samples were taken to determine the content of heavy metals (Cu, Zn, Pb, Co, Mo, Ni). In the following spring, the area was planted with potatoes, eggplant, and peas. A rather high yield was obtained. Analysis of plant samples showed that the content of heavy metals does not exceed the permissible level of the international food safety standard. At the same time, soil studies were carried out in the adjacent areas of the Sotk mine, located to the southeast of Lake Sevan. It was revealed that due to the increase in the volume of the mining industry and the amount of rock dumps, the organoleptic and chemical indicators of the waters of the Sotk and Masrik rivers deteriorated. Compared to the previous decade, the amounts of suspended particles per 1 L of water have increased by 210…317.0%, in the waters of Sotk—by 32.1 mg/L, and in the waters of Masrik—by 13.2 mg/L. The same tendency is observed regarding the amounts of nitrates, sulfates, and hydrogen index, which is mainly due to the chemical composition of rocks. They contain a large amount of Ca, K, Na, Mg, etc. This trend is especially noticeable along the rivers, where intensive agriculture, primarily livestock farming is carried out. The material of the work solves a complex of environmental and economic problems. It is aimed at ensuring environmental safety, improving the ecological and resource properties of soils, increasing the productivity of cultural phytocenoses and the sanitary and hygienic quality of food products. Full article