Intensity of Soil Pollution by Toxic Substances Depending on the Degree of Its Washout

Abstract

A significant degree of ploughness of agricultural lands of Ukraine has led to increased erosion and the creation of soils of varying degrees of washout, which leads to dehumification and contamination of soils with toxic substances. Therefore, the purpose of the study was to establish the features of horizontal migration and accumulation of heavy metals of lead, cadmium, copper, and zinc, trace elements of boron and manganese, radionuclides of caesium and strontium on podzolic heavy loamy chernozems with varying degrees of washout: non-eroded, weak and medium washout, conditioned by the development of erosion processes. During the study, spectrophotometric, colorimetric, gamma-spectrometric, and radiochemical methods were used to determine the content of toxic substances in the soil. The study results showed that on slightly washed soils, the content of humus is 12.9% less, easily hydrolysed nitrogen – 13.3%, mobile forms of phosphorus – 51.1%, mobile potassium – 34.9% less than on slightly washed soils. The humus content on medium-washed soil was 8.8% less than on lightly washed soil, easily hydrolysed nitrogen – 14.3% less, mobile phosphorus – 15.3% more, mobile potassium – 42.9% more. A strong horizontal migration of mobile lead forms in washed podzolic heavy loamy chernozem was established, which increases with increasing degree of soil washout with the content of mobile lead forms on medium-washed soil by 24% more than on non-eroded soil. The same dependence was established on the content of mobile forms of zinc in the soil, with their predominance on medium-washed soil by 17 %, compared to non-washed. The content of mobile forms of copper is lower on slightly washed soil, compared to non – washed soil by 5%, boron – 18.8% less on non-washed soil, compared to medium-washed, and the content of mobile forms of manganese increases by 3.3% from slightly to medium-washed soil. It was also found that the concentration of caesium decreased by 25.6% on medium-washed soils, compared to non-washed ones