Influence of flow on thawing of underwater slopes and the pace coastal erosion of rivers, occurring in the permafrost zone

In the hydraulic laboratory of department of architecture & civil engineering RUDN University was performed studies of destruction of underwater and above-water coastal slopes in conditions simulating permafrost, depending on the soil type, the initial slope, and the slope angle. It was shown by authors, the speed of erosion of the underwater slope lags behind the speed of thawing of frozen ground. Water flow's influence is much higher than the impact of other factors (temperature, effect of wind, solar radiation), resulting in the formation of the washout niches. Thus, the main goal of the work was to identify the most important factors that affect on the changes of the river bed in permafrost zone.Keywords: experiment; frozen ground; erosion; water flow; permafrost zone

Biological diversity and ecosystem services of the technosols of mining areas

The development of the concept of disturbed lands recultivation as a set of activities for restoring of ecosystem services is an actual scientific problem. The principles of the formally assessment of ecosystem services for the harmonization and control of the behaviour of technoagroecosystems were developed within the frame of the ecosystem paradigm to achieve a significant efficiency of the re-cultivated land functioning under environmental safety conditions and to achieve the objectives of biodiversity conservation. A set of variables, describing the environmental properties of the technosols, was analyzed by the principal component analysis in order to reduce the dimension of the properties space and to determine the main directions of the corresponded variation of the ecological properties of the technosols. The results of the analysis suggested that the feature space, which consists of 30 initial indicators, can be described with the help of seven pricipal components. The extracted principal components reflected the prevailing agreed trends of varying environmental properties of technosems. The principal components were statistically correct predictors, which can be investigated to explain the properties of the soil macrofauna communities. The principal components also had an ecological content as the markers of coordinated changes of the soil properties and plant communities. The estimation of the principal component influence on the soil macrofauna allowed to determine peculiarities of the integration of soil animals into ecological processes in technosems and their role in ecosystem services. The principal components had a differential ability. Each of them indicates the peculiarities of a combination of ecosystem services, which is typical for an individual tehnosems or a particular group. The functional peculiarities of the soil invertebrate communities, responsible for the implementation of ecosystem services, were affected by the aggregate structure of technosls, as well as react to electrical conductivity of the soil, features of ecological regimes of the mineral nutrition and humidity of soils. The variation of the environmental parameters in integral form denoted by the principal component 2 was within the optimum of the pedobiont zone. This result allows us to argue, that technosols cannot be identified as a total extreme location. The formation of the optimal conditions for certain groups of macrofauna community was the result of the soil forming process that took place since the creation of technosols. The technosol types explained 5.68% of the macrofauna community grouping, which testifies to the specificity of each type of technosols as habitat for soil animals. Along with the specific peculiarities of technosols, there was a dynamic of processes, which in this way react to the groups of macrofauna in different types of technosols. The structuring effect of the technosol type on the invertebrate community was considerably inferior to the influence of variation of environmental regimes, which are common for all types of technosols. The perspectives of further researches are related to solving the issue of the mapping of ecosystem services of agricultural and technogenic transformed territories at different scale levels. Also an important scientific and practical problem is the development of procedures for monetary evaluation of the ecosystem services

Моделирование деформаций русел, сложенных мёрзлыми породами, при повышении температуры окружающей среды

This paper is devoted to investigation of the influence of river flow and of the temperature rise on the deformation of the coastal slopes composed of permafrost with the inclusion of ice layer. The method of investigation is the laboratory and mathematical modeling. The laboratory experiments have shown that an increase in water and air temperature changes in a laboratory analogue of permafrost causes deformation of the channel even without wave action, i.e. at steady-state flow and non-erosive water flow velocity. The previously developed model of the bed deformation was improved to account for long-term changes of soil structure with increasing temperature. The three-dimensional mathematical model of coastal slopes thermoerosion of the rivers flowing in permafrost regions, and its verification was based on the results of laboratory experiments conducted in the hydraulic tray. Analysis of the results of mathematical and laboratory modeling showed that bed deformation of the rivers flowing in the permafrost zone, significantly different from the deformation of channels composed of soils not susceptible to the influence of the phase transition «water-ice», and can occur even under the non-erosive velocity of the water flow.Работа посвящена исследованию влияния речного потока и повышения температуры воды на деформации береговых склонов, сложенных многолетнемёрзлыми породами с включением пластов льда. Методы исследования – лабораторное и математическое моделирование. Лабораторные эксперименты показали, что при повышении температуры воды и воздуха изменения в структуре лабораторного аналога многолетнемёрзлого грунта вызывают деформации русла даже без волнового воздействия, т.е. при стационарном режиме течения и неразмывающих скоростях водного потока. В связи с этим возникла необходимость усовершенствования разработанной ранее модели деформации русла с целью учёта долгопериодных изменений структуры грунта при повышении температуры воды. В основу трёхмерной математической модели термоэрозии береговых склонов рек, протекающих в районах развития многолетней мерзлоты, и её верификации положены результаты лабораторных экспериментов в гидравлическом лотке. Анализ результатов математического и лабораторного моделирования показал, что русловые деформации рек, протекающих в криолитозоне, значительно отличаются от деформаций русел, сложенных грунтами, не подверженными влиянию фазового перехода «вода–лёд», и могут наблюдаться даже при неразмывающих скоростях водного потока

Impact of graft-versus-host disease prophylaxis on immune reconstitution in patients after allogeneic hematopoietic stem cell transplantation

The graft-versus-host disease (GVHD) is among the most common complications after hematopoietic stem cell transplantation (allo-HSCT). The main tools for GVHD prevention remain calcineurin inhibitors (cyclosporin A, tacrolimus), methotrexate, mycophenolate mofetil. Upon implementation of reduced-intensity conditioning regimens, antithymocyte globulin was widely introduced. However, negative effects upon reconstitution of T-cell immunity have been noted, thus increasing risk of severe infectious complications and disease relapse. With extended practice of HSCT from alternative (partially matched or haploidentical) donors, cyclophosphamide was increasingly used. Our aim was to study reconstitution of immune cell subpopulations in the patients undergoing bone marrow transplantation (BMT), when using different GVHD prophylaxis regimens, including the schedules with post-transplant CP usage. The study concerned 44 cases classified into 2 groups. The first one included patients with standard immunosuppressive therapy, antithymocyte therapy, cyclosporine A, methotrexate, mycophenolate mofetil. The second group included the patients who received CP as immunosuppressive drug combined with other treatments (cyclosporine A, methotrexate, mycophenolate mofetil). At specified control terms, (D+14, +30, +60, +90) the blood leukocyte subpopulations were assayed by means of multicolor flow cytometry. Absolute counts of CD4+ cells in HSCT recipients treated with CP post-BMT proved to be sufficiently lower at D+14 and +30, than in those treated with classical immunosuppressive therapy. However, at later terms, (D+60, +90), these differences were not observed. Moreover, in CP-treated bone marrow recipients, absolute numbers of CD8+ cells was significantly higher, compared to the patients who received conventional GVHD prophylaxis. Reconstitution of the studied lymphocyte populations in hematopoietic cell recipients did not depend on the GVHD prophylaxis regimen. Usage of CP combined with bone marrow as a source of stem cells, brings about sufficient decrease of some cell populations (CD4+; CD8+; NK cells) at early terms post-transplant. Administration of CP combined with hematopoietic stem cells as the source of hematopoietic graft seems to be more reasonable

Assessing the role of thermal erosion in channel deformation processes in rivers of permafrost zone

The study is focused on the deformations caused by the impact of water flow in a river channel composed of melt-able permafrost rocks. It is based on the results of laboratory and mathematical simulation. The results of numerical calculations are compared with data of laboratory and field observations. The study shows that a comprehensive and adequate model of river channel deformations should take into account not only ablation, but also other factors, including heat transfer in the soil, sediment transport, and bank slope collapses. Numerical experiments with an improved mathematical model, applied to long time intervals, have shown that the differences between the averaged deformations, calculated by a model of ablation alone, i.e., ignoring bank slope collapses and sediment transport, and a comprehensive model can be considerable. Experiments in a hydraulic flume were good enough to reproduce the effect of delayed collapse, consisting in nonsimultaneous impacts of channel-forming rock melting and a freshet. © 2020 The Authors, published by EDP Sciences

INFLUENCE OF FLOW ON THAWING OF UNDERWATER SLOPES AND THE PACE COASTAL EROSION OF RIVERS, OCCURRING IN THE PERMAFROST ZONE

In the hydraulic laboratory of department of architecture & civil engineering RUDN University was performed studies of destruction of underwater and above-water coastal slopes in conditions simulating permafrost, depending on the soil type, the initial slope, and the slope angle. It was shown by authors, the speed of erosion of the underwater slope lags behind the speed of thawing of frozen ground. Water flow's influence is much higher than the impact of other factors (temperature, effect of wind, solar radiation), resulting in the formation of the washout niches. Thus, the main goal of the work was to identify the most important factors that affect on the changes of the river bed in permafrost zone

INFLUENCE OF FLOW ON THAWING OF UNDERWATER SLOPES AND THE PACE COASTAL EROSION OF RIVERS, OCCURRING IN THE PERMAFROST ZONE

In the hydraulic laboratory of department of architecture & civil engineering RUDN University was performed studies of destruction of underwater and above-water coastal slopes in conditions simulating permafrost, depending on the soil type, the initial slope, and the slope angle. It was shown by authors, the speed of erosion of the underwater slope lags behind the speed of thawing of frozen ground. Water flow's influence is much higher than the impact of other factors (temperature, effect of wind, solar radiation), resulting in the formation of the washout niches. Thus, the main goal of the work was to identify the most important factors that affect on the changes of the river bed in permafrost zone

The Seasonal Deformations of the Coastal Slopes in the Permafrost Zone

With the recent global warming, especially in the northern hemisphere, requires expansion of research on the modeling and prediction of the destructive processes of coastal water bodies located in the permafrost. We have considered a set of interrelated factors that have a significant impact on deformations of the coastal slopes in the permafrost zone under conditions of seasonal changes in the environment. The model consists of several blocks: the thawing of frozen soil and the occurrence of melt flow, the division of the precipitation on the infiltration and the catchment (surface fluxes) and the seasonal melting of snow as a type of the incoming rainfall, the impact of surface runoff erosion on the coastal slope