Minimum length of suspended sediment yield time-series for a proper estimation of spatio-temporal variability of erosion rates in river basins

River suspended sediment yield (R) is one of the proxies of erosion activity and mechanical denudation in river basins, that can vary greatly both in space and time. A number of R-databases have been collected and permitted to reveal regional and global patterns of erosion. One of the main shortcomings of these databases is the high presence of relatively short lime-scries, which influences greatly the reliability of resultant assessments of spatial erosion patterns. It is necessary to determine the minimum time-series length reliable for assessment of suspended sediment yield spatio-temporal variability, erosion rate mapping and theoretical issues. The author's original method was used to analyze long term time-series from 84 hydrological stations over the former USSR and determine the I values of 9.1 ± 1.2 and 7.611.2 years for assessment of spatial and temporal variability oftf, rcspcciivcly. In case of spatial variability of R in small river basins, reliable time series are 10+ years in lowland landscapes and 6-7 years in highlands, for medium and large basins the /-values are 5 and 10 years respectively. Given that the majority of hydrological stations are located in lowlands and low mountains, the author recommends to base regional and global hydrogeomorphological studies on suspended sediment yield time series not shorter than 10-11 years

Aeolian-Accumulative complex sarykum as a unique geomorphic object Of Russia: Structure, genesis and sands sources

Acolian-accumulativc complcx Sarykum is one of the highest isolated (i.e. formed away from the deserts) sandy land forms in Eurasia, located within the Tcrck-Sulak lowland plain at the north-eastern foothill of the Caucasus Mountains, 16-17 km towards WNW of the Makhachkala City port of Caspian Sea (Republic of Dagestan, Russia). On the basis of particle size distribution and mineralogical analysis of 59 sandy samples, the heterogeneous structure of the complcx is defined. The coarscst sandy material (modal values arc 352 micron and more) composes the central dunc-ridgc segment of Sarykum (of so-called Great (or West) Sarykum). The further from the dune constructions to the periphery, the thinner the average dimension of the sand particles and smaller the modal values (249 micron and less) of their granulomere spectra. This grain size distribution can be explained not only by windy sorting of the sands and further acolian recast of dunc-ridgc segment, but also by spatial features of the facial changes during the period of initial sandy accumulation, and also by the differences in composition of rocks, which were the sources of denudation. In the vertical structure of Sary kum the heterogeneity is also expressed. It is associated with temporary changcs of sandy sedimentation conditions in the region. So, the dunc-ridgc segment of Great Sarykum can be represented as a system of consistently accumulated sandy layers (lenses?) (which includes the gravelly sands), which differ in composition and age, having apparently the coarscst content in the middle part of its vertical geological cross-section. The material of overwhelming majority of the selected samples belongs to mineral group of quartz sands (quartz contcnt is over 90%) and subgroup of quartz subarkosc (quartz contcnt is 80-90%). Moreover, the acolian (deflated) sands of the dunc-ridgc segment and its underlying cross-bcddcd sands of Great Sarykum entirely belong to the first group; the hilly and peripheral sands, which characterized by fine granulomctry, refer to the second mineral subgroup. The Sarykum's structure is due to the combination of gravelly sands, formed by the river Shura-Ozcn' dcltaic accumulation in the Late Quaternary, and sandy (with gravels and pcbbccs) deposits proluvially and dcluvially dislocated to the recent Sarykum massif territory from the slopes of the nearby Narat-Tubc mountain range. The mixing of originally and compositionally different sediments that formed the Sarykum complcx, likely have the complicated history, following by the staged changcs of the periglacial landscape-climatic conditions in the Late Quaternary

Suspended sediment yield from continents into the World Ocean: Spatial and temporal changeability

Attempts have been made to determine the suspended sediment yield from rivers of the various continents and islands into the World Ocean. Its differentiation into natural and anthropogenic components, and analysis of its contemporary trend variability were undertaken. The total global suspended sediment yield into the World Ocean equals 15.5 × 109 t year-1. The main suppliers are continental Asia and the islands of the west and southwest parts of the Pacific (their contribution to the total global suspended sediment yield into the World Ocean is 73.4%). The least sediment is supplied by Australia (1.1%). Recent human activity has increased suspended sediment yield into the World Ocean by 2.6 times. The largest anthropogenic increase of suspended sediment yield found is on the islands of the west and southwest parts of the Pacific (by 3.7 times) and in Europe (by 3.4 times); the least intensification characterizes South America (by 1.2 times). The analysis of long-term time series of suspended sediment yield shows that during the second half of the 20th century a rising trend of erosion intensity and suspended sediment yield prevailed in South and Central America, East Africa, West Europe, South and South-East Asia and Australia. A reduction of suspended sediment yield took place in East Europe, northwest and eastcentral parts of Asia and west part of North America. The main factor determining these global scale changes is diverse human activity

Utilization of the wastes of vital activity

The recycling of wastes from the biological complex for use in life-support systems is discussed. Topics include laboratory equipment, heat treatment of waste materials, mineralization of waste products, methods for production of ammonium hydroxide and nitric acid, the extraction of sodium chloride from mineralized products, and the recovery of nutrient substances for plants from urine

On Quality of a Weld Bead Using Power Wire 35v9h3sf

The effect of introducing carbon-fluorine containing additives and nickel to flux-cored wire 35V9H3SF on its structure, micro hardness of martensite, hardness and wear rate of a welded layer has been investigated. It has been proven that carbon-fluorine additions to a powder mixture increase the hardness of the deposited layer and its wearing strength. Nickel adding increases the hardness of both martensite and the deposited layer, and reduces abrasion wear. Introducing carbon-fluorine containing additives to the powder mixture can reduce the pore formation and lower the level of impurity with nonmetallic inclusions; and nickel adding can lead to austenite having a finer grain size

The contemporary height of aeolian accumulative complex Sarykum (republic of Dagestan) and the causes of its change

The aeolian accumulative complex Sarykum is the Russia's largest and one of the highest in Eurasia sandy massif, which formed away from large deserts. It is located in the Terek-Sulak lowland at the foothill of northeastern mega-slope of the Greater Caucasus. Since the end of the 19th century until the present time the highest dune of the complex has reduced in the height more than by 16 m (since the middle of the 20th century - by 5.7 m) - from 262 to 245.8 m. According to the authors, the reduction was caused mainly by natural (first of all by climate) change in the region. So, the average annual number of moderate, strong and very strong winds had here reduced by 41% (from 1966-1986 to 1987-2015), especially at the summer (in the driest period with strongest deflation) and the winter seasons, and the average annual precipitation had increased by 25% between the same periods. The latter fact contributed to wide expansion of grass and shrub vegetation on the slopes of Sarykum and increased a deflation resistance of its sands. In addition, the strong earthquake (May 14, 1970) with the epicenter that located nearby the Sarykum could be the reason of the dune height reduction. Against the background of the natural changes, the potential role of human activities is manifested through the sand quarrying in the early 20th century and the creation of protected (reserve) status within of the Great (West) Sarykum since late 1980s

Contribution of climate and land cover changes to reduction in soil erosion rates within small cultivated catchments in the eastern part of the Russian Plain during the last 60 years

© 2018 Elsevier Inc. The eastern part of the Russian Plain is an important agricultural region of European Russia with high proportion of cultivated lands in the steppe, forest-steppe and forest (southern part) landscape zones. Soil erosion is the main process of land degradation and surface water contamination there. Climate and land cover changes have been observed in this region during the last 30 years. However, field quantitative assessments of soil erosion rates are not available for the eastern part of European Russia due to the lack of monitoring data as well as the evaluation of erosion/deposition processes in cultivated catchments using other field methods. Three representative small cultivated catchments with high (> 80%) proportion of cultivated lands were selected in the forest (southern part), forest-steppe and steppe zones of the study region to evaluate sedimentation rates in dry valley bottoms of the catchments for two-time intervals (1963–1986 and 1987–2016) based on the application of the bomb-derived and Chernobyl-derived137Cs isotope for sediment dating. The 3–4 depth137Cs profiles were used to assess the sedimentation rates within the each investigated catchment. It was established that the sedimentation rates have considerably decreased (at least 2–3 times) over the last 30 years compared to 1963–1986 in all the investigated catchments. This is in agreement with results of erosion rate calculations using erosion models for the forest zone, however not consistent with erosion rates assessments for the forest-steppe and steppe zones. According to the model calculations, erosion rates show a slight decrease in the forest-steppe zone and increase in the steppe zone. The reduction in surface runoff during snowmelt period is one of the reasons for decrease in erosion rates within cultivated slopes for all the investigated catchments. The increase in proportion of perennial grasses in the regional crop rotation is another important reason for the decrease in erosion rates for the catchment located in the south of the forest zone. The importance of land cover changes in a major decrease of soil losses from the cultivated fields of the investigated catchments located in the forest-steppe and steppe zones cannot be identified due to the lack detailed information about crop rotation for those particular sites. However, available regional information about crop rotation changes for the two-time intervals (1960–1980 and 1996–2012) do not explain very high reduction in sedimentation rates in the dry valley bottoms after 1986