The paper deals with the issues of determining the reference value of specific activity of cesium-137 of Chernobyl origin when applying the radiocesium method to assess the loss of gray forest soil in the areas of spread of the microrelief of paleocryogenic origin in the periglacial region of the upper Oka basin. Paleocryogenic microrelief is recognized in spring satellite imagery available on Google EarthTM. The necessity of choosing a reference plot for a specific field that differs in microrelief, exposure, and the nature of soil cultivation is substantiated. The authors analyze the data, which they obtained during the field research in 2016-2019, on three agricultural fields located on the arable slopes of the northern and southern exposure in the upper Oka basin within the Orel district of the Orel Region. Three experimental plots, selected in close proximity to one another, differed both in exposure and in the content of humus, labile phosphorus and radiocaesium in the arable layer. Layer-by-layer soil sampling at block elevations within the reference plots located on watershed surfaces, gamma-spectrometric and agrochemical analyzes of soil samples allowed us to draw a number of systematically important conclusions. The first is that the reference value of radiocaesium in the arable layer should be determined within block elevations on the watershed surface of the slope or on inter-valley micro-water divisions on the water-divide surface (if it is not possible to select a reference plot on the watershed surface). The second is that the dimensions of the reference plots are determined by the size of the block elevations (the sizes of blocks in the area under study are 10-20 m). The third is that the reference value of radiocaesium should be determined individually for each field that differs in exposure and in the nature of the soil treatment. In the experimental plot, the reference value of the specific activity of cesium-137 increases in the following order: a field located on the water-divide surface of the northern exposure slope, with a grain rotation, with regular fertilizing (130.5 Bq/kg) — a field located on the watershed surface of the eroded slope southern exposure (174.7 Bq/kg) — a field located on the water-divide surface of a less fertilized and less eroded slope of the northern exposure (180 Bq/kg). The results of the study show that the use of the radiocaesium method in periglacial areas requires testing a fundamentally new approach to its implementation: at the stage of determining the reference value of radiocaesium, it is necessary to take into account the polygonal-block structure of the watershed surfaces.
ABSTRACT:In our study we estimate relationships between quantitative parameters of relief, soil runoff regime, and spatial distribution of radioactive pollutants in the soil. The study is conducted on the test arable area located in basin of the upper Oka River (Orel region, Russia). Previously we collected rich amount of soil samples, which make it possible to investigate redistribution of the Chernobyl-origin cesium-137 in soil material and as a consequence the soil runoff magnitude at sampling points. Currently we are describing and discussing the technique applied to large-scale mapping of the soil runoff. The technique is based upon the cesium-137 radioactivity measurement in the different relief structures. Key stages are the allocation of the places for soil sampling points (we used very high resolution space imagery as a supporting data); soil samples collection and analysis; cali bration of the mathematical model (using the estimated background value of the cesium-137 radioactivity); and automated compilation of the map (predictive map) of the studied territory (digital elevation model is used for this purpose, and cesium-137 radioactivity can be predicted using quantitative parameters of the relief). The maps can be used as a support data for precision agriculture and for recultivation or melioration purposes.
Геоинформатика и картографирование в охране окружающей среды и обеспечении экологической безопасности 323 УДК 577.346 DOI: 10.24057/2414DOI: 10.24057/ -9179-2017 Л. КЛЮЧЕВЫЕ СЛОВА:микрорельеф, смыв почвы, эрозионная сеть, цезий-137 ВВЕДЕНИЕ В условиях изменяющегося режима увлажнения оценка роли древней флювиальной се-ти в современных эрозионных процессах на распахиваемых поверхностях междуречий ста-новится всё более актуальной. Ложбинная сеть в перигляциальных областях Русской равни-ны является наиболее распространённым типом рельефа. Происхождение её, как показано многочисленными исследованиями [Величко и др
Abstract. The paper discusses a problem of complex data application when accounting erosion network elements to study soil runoff and soil material redistribution on arable slopes. It is needed to estimate and account contribution of microrelief landforms to the sediment (washed out soil material) redistribution on arable areas to enhance accuracy of estimation of the soil runoff and accumulation. However, microrelief landforms are hardly detected on topographic maps and plans used traditionally in land management. For example, temporary streams formed in plowing furrows (in the case of along-slope plowing) can be detected only when survey and soil sampling data are attracted, or (partially) using remote sensing data.Due to such a context, we discover integrated analysis of map data (digital maps represented and processed in GIS environment), data of gamma-spectrometric analysis of the soil samples, and very high resolution satellite imagery, which is aimed onto detection of the role of stable and dynamically changing microrelief landforms in soil material redistribution.
The introduction of the principles of adaptive (precision) farming into the practice of land use makes it relevant to develop methods for calculating soil losses by morphometric indicators of the relief for plowed slopes with a complex surface. The paper considers the possibilities of applying the radiocesium method to the calculation of soil losses due to erosion in areas of agricultural fields with plowed soils. The purpose of the work is to develop a methodology for calculating erosional soil losses by the specific activity of caesium-137 (as an indicator of soil losses) depending on the morphometric indicators of the relief (calculated by GIS tools) for a local experimental site of an agricultural field, the soils on which are classified as plowed. The experimental site is located on an agricultural field, which is in the basin of the Sukhaya Orlitsa River in the Orel District, Orel Region. The article presents the results of approbation of the calculated dependence (previously developed for depressions with a watershed area of 50,000 m²) for a site with plowed soils. It is stated that the calculation according to the tested equation gives large errors. The authors proposed an original dependence of the activity of cesium-137 on the collection area, calculated in the GIS, developed for a local area with plowed soils. A check on independent material showed that the calculation error according to the original dependence did not exceed 20 % in 73 % of cases. A map of soil losses for the site of plowed soils, built in GIS based on the developed dependence, is presented.
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