Showing papers by "Russian State Agricultural University published in 2013"

Urban soil organic carbon and its spatial heterogeneity in comparison with natural and agricultural areas in the Moscow region.

Abstract: Soils hold the largest carbon stock in terrestrial ecosystems. Soil organic carbon (SOC) is formed under a combination of bioclimatic and land-use conditions. Therefore, one would expect changes in SOC stocks with land use changes like urbanization. So far, the majority of regional studies on SOC stocks exclude urban areas. The urban environment has a unique set of specific features and processes (e.g., soil sealing, functional zoning, settlement history) that influence SOC stocks and its spatial variability. This study aims to improve our understanding of urban SOC in comparison with agricultural and natural areas for the Moscow region (Russia). SOC content was studied in different land use types, soils, and urban zones through stratified random sampling. Samples of topsoil (0–10 cm) and subsoil (10–150 cm) were taken at 155 locations. SOC contents were significantly higher in urban areas compared with non-urban areas (3.3 over 2.7%). Further analyses proved that the difference can be explained by the so-called “cultural layer”, which is the result of human residential activity and settlement history. SOC contents in the urban environment presented a very high spatial heterogeneity with standard deviations of urban SOC considerably higher than those for agricultural and natural areas. Soil depth, soil type and land-use factors had a significant influence on SOC variability determining more than 30% of the total variance. SOC contents in urban topsoil were mostly determined by soil type. In natural and agricultural areas soil type and land-use determined SOC contents. The results confirm the unique character of urban SOC and the need to reconsider established scientific and management views on regional SOC assessment, taking into account the role of urban carbon stocks.

Method of studying the degradation of soil macroaggregates based on the self-absorption of 137 Cs β radiation

Abstract: A method was proposed for studying the degradation of soil aggregates in time from the absorption of 137Cs β-radiation by a soil sample. The method is based on the difference in the recorded β radiation intensities depending on the distribution of 137Cs between the surface of the aggregates and the nonaggregated soil material. At the localization of the radionuclide on the surface of the soil aggregates, the counting rate will significantly exceed that for the samples containing a similar amount of the radionuclide uniformly distributed throughout the soil volume. This effect is due to the insignificant range of the mild β radiation in the soil (less than 1 mm depending on the radiation energy). Relatively clear calibration graphs under the selected conditions of the radiometric measurements were obtained for the aggregates whose sizes were in the range of 3–10 mm. Under natural conditions, the 7- to 10-mm aggregates of a dark gray clay loamy soil under a forest belt decomposed by 50–65% at a depth of 10 cm and by 23–32% at a depth of 30 cm. The more intense degradation of the soil aggregates of the same size was observed under the conditions of a pot experiment.

On the trajectories of a mass point on a rotating surface

Abstract: N. E. Zhukovskii proposed a special method [1] for determining the trajectories of amass point (particle) on a plane in the field of potential forces. In [2], this method was generalized to the case of particle motions on curvilinear surfaces. In the present paper, this method is generalized to the case in which the surface, together with the field of potential forces, rotates about a fixed axis. Several examples are considered.

On the damping of nonlinear vibrations in some second-order dynamical systems

Abstract: This paper continues the study of damping of nonlinear vibrations in second-order dynamical systems for the case considered in [1].