Перспективы рыбохозяйственного использования малых озер Новосибирской области

The paper explores 11 lakelets in order to design the recommendations on stocking them with certain types of fish. Zooplanktone is represented by 32 species from three systematic groups. Zooplankton species diversity varies from 5 to 16. The dominant complex of species is very different.. In some lakes, the leading role belongs to the cladocerans. In other lakes, different species of copepods play a dominant role. The rotifiers dominate in two lakes. The quantitative indicators of zooplankton in the lakes differ significantly from each other. The highest number of zooplanktone is 1312,7, the minimum-26,7 thousands units / m3. The maximum zooplankton biomass was observed in the most saline lake where its value reached 70,7 g/m3. The least biomass was 0.1 g / m3. The zoobenthos contained 29 species from 11 large taxonomic groups. The most numerous group (19 species, 65.5% of the total number of taxonomic composition of benthic animals) consisted of chironomids, oligochaetes (3) and biting midges (2). Other groups consisted of one specie. The number of species in the lakes varied from 2 to 15. The highest parameters of the number was 973 samples/m2, biomass - 7.33 g/m2; the lowest parameters for the number and biomass were 26 samples/m2 and 0.16 g/m2 . According to zooplankton biomass and capacities for breeding fish lake planktophagous, 2 lakes out of 11 refer to those which have insufficient nutrients; other lakes refer to average lakes with sufficient nutrients to extremely nutrient lakes. Taking into account regional standards, equal to 50 kg/ha when breeding Peled, the authors recommend the Ploskoe lake, the Bogatikha, the Gorbunechnoe and the Sladkoe for commercial fish breeding. Considering development of zoobenthos, 7 lakes out of 11 belong to those which have insufficient nutrients. The Ploskoe lake, the Kamennoe, the Kalach and the Sladkoe are average lakes with sufficient nutrients and extremely nutrient ones. The authors recommend them for breeding carp and common carp.Исследовано 11 малых озер с целью рекомендаций по зарыблению их определенными видами рыб. Зоопланктон представлен 32 видами из трех систематических групп. Видовое разнообразие зоопланктона составляет от 5 до 16. Доминирующий комплекс видов также различается, как и видовое разнообразие. В ряде озер руководящая роль принадлежит ветвистоусым ракообразным. В некоторых озерах доминирующую роль играют разные виды веслоногих ракообразных. В двух озерах доминируют по численности коловратки. Количественные показатели зоопланктона в озерах значительно отличаются друг от друга. Наиболее высокая численность 1312,7, минимальная - 26,7 тыс. экз/м 3. Максимальная биомасса зоопланктона наблюдалась в наиболее осолоненном озере, ее величина достигала 70,7 г/м 3. Минимум биомассы составлял 0,1 г/м 3. В составе зообентоса отмечено 29 видов из 11 крупных таксономических групп. Самой многочисленной группой (19 видов, 65,5 % от общего количества таксономического состава донных животных), являются хирономиды, далее следуют олигохеты (3) и мокрецы (2). Остальные группы представлены одним видом. Количество видов в озерах колебалось от 2 до 15. Самые высокие средние количественные показатели численности 973 экз/м 2, биомассы - 7,33 г/м 2, самые низкие - 26 экз/м 2 и 0,16 г/м 2. По величине биомассы зоопланктона и потенциальным возможностям для выращивания рыб-планктофагов 2 озера из 11 относятся к малокормным, остальные от среднекормных до весьма высококормных. Учитывая принятые нормативы региона, равные 50 кг/га, при плановом выращивании пеляди рекомендуются для целей товарного выращивания озера Плоское, Богатиха, Горбунечное и Сладкое. По развитию зообентоса 7 озер из 11 относятся к малокормным. Озера Плоское, Каменное, Калач и Сладкое являются средне- и высококормными и рекомендуются для выращивания сазана и карпа

Experimental modelling of a mine working failure under nonuniformly distributed compression

This paper presents a theoretical and experimental study of the fracture of a quasi-brittle geomedium containing a cylindrical opening and subjected to a nonuniformly distributed compressive load. Laboratory tests are carried out using hydrated gypsum plaster as a model rock-like material. High-strength plaster specimens demonstrate brittle fracture, while specimens made of plaster of Paris show quasi-brittle fracture. In this case, the application of the known criteria does not allow obtaining satisfactory estimates of the fracture load. New nonlocal fracture criteria are proposed, which are the development of the average stress criterion, and point stress criterion, and which contain a complex parameter that characterizes the size of the fracture process zone and accounts not only for the material microstructure, but also plastic properties of the material, geometry of the opening, and loading conditions. The calculation results are in good agreement with the resulting experimental data

Nonlocal Criteria for Brittle and Quasi-Brittle Fracture of Geomaterials and Rocks

Nonlocal criteria are used for prediction materials and rock mass failure near stress concentrations (pores, faults, openings, excavations). A common property of nonlocal fracture criteria is the introduction of the intrinsic material length characterizing its microstructure, which allows one to describe the size effect in conditions of stress concentration. At the same time the scope of their application is limited to cases of brittle or quasi-brittle fracture with a small fracture process zone. To expand the scope of the criteria for cases of fracture with a developed fracture process zone, it is proposed to abandon the hypothesis of the size of this zone as a material constant, associated only with the material structure. New fracture criteria are proposed, which are the development of the average stress criterion, and point stress criterion, and which contain a complex parameter that characterizes the size of the fracture process zone and accounts not only for the material structure, but also plastic properties of the material, geometry of the sample, and its loading conditions. Expressions are obtained for the critical pressure in the problem of the formation of tensile cracks under compression in the samples of geomaterials with a circular hole. The calculation results are in good agreement with the experimental data on the fracture of drilled gypsum plates

Study of Lake Baikal ice cover from radar altimetry and in-situ observations

Comparison of ENVISAT and SARAL missions data shows that AltiKa can be successfully used for ice discrimination methodology and extension of ice conditions time series. Due to shorter wavelength and large bandwidth (480 MHz) which leads to a higher sensitivity to different surface conditions, AltiKa shows more clearly the separation between open water and various ice types. We observe significant decrease of backscatter (25–30 dB) in late spring for both ENVISAT and SARAL and discuss it in the context of ice metamorphism. There is a clear need to continue and expand our dedicated field studies of lake Baikal ice cover to better assess influence of ice structure on altimetric signal

Study of Lake Baikal ice cover from radar altimetry and in-situ observations

Comparison of ENVISAT and SARAL missions data shows that AltiKa can be successfully used for ice discrimination methodology and extension of ice conditions time series. Due to shorter wavelength and large bandwidth (480 MHz) which leads to a higher sensitivity to different surface conditions, AltiKa shows more clearly the separation between open water and various ice types. We observe significant decrease of backscatter (25–30 dB) in late spring for both ENVISAT and SARAL and discuss it in the context of ice metamorphism. There is a clear need to continue and expand our dedicated field studies of lake Baikal ice cover to better assess influence of ice structure on altimetric signal

Giant ice rings on lakes Baikal and Hovsgol: Inventory, associated water structure and potential formation mechanism

Observations of giant ice rings on Lake Baikal (Russia) have recently sparked scientific and public interest. However, there is still no clear consensus on their origins. Here, we provide an inventory of the ice rings based on satellite imagery and photography for 1974–2014. We have identified 45 rings on Lake Baikal (compared with 13 previously known) and also for the first time four rings for the neighbouring Lake Hovsgol (Mongolia). The results of our hydrographic surveys beneath the ice rings in Lake Baikal in 2012–2014 and in Lake Hovsgol in 2015 show the presence of warm double-convex lens-like eddies before and during manifestation of ice rings. We suggest that these eddies are the driving factor for the formation of ice rings in these lakes. We reassess the existing hypotheses of ice ring formation and discuss the potential mechanisms of eddy formation