Possibility of the secondary contamination of chernozem soils leached with nickel in the result of irrigation amelioration

Aim. The effect of irrigation on the properties of leached chernozem, as well as on the possibility of secondary soil contamination with nickel (Ni), was studied. An important geochemical feature of the region in which the study was conducted is the enrichment of the soil-forming rocks Ni. As is well known, soil-forming rocks have a direct impact on the chemical composition of soils and water, and indirectly on the content of an element in living organisms. Methods. In order to determine the possible contamination of the soil by Ni as a result of irrigation with natural waters containing this element in large quantities, the main chemical and physico-chemical indicators of the studied chernozems were studied in detail. The gross content and profile distribution of Ni, as well as its exchange compounds in leached chernozem heavy loamy, intensively used in irrigated agriculture, have been determined. The obtained data were compared with indicators obtained in similar soils located on the deposit (background areas). Results. It is shown that under conditions of irrigation in chernozem there is a decrease in the percentage of humus and an increase in the capacity of the humus profile. In irrigated soils there is a decrease in pH and an increase in hydrolytic acidity. It was revealed that the maximum Ni content is noted in the upper horizon of irrigated black soil. Down the profile, a gradual decrease in the metal content occurs, and in the soil-forming rock, there is a second maximum in the profile distribution of Ni. This phenomenon is associated with the enrichment of soil-forming rocks element. Main conclusions. The obtained data on the gross content of Ni and its exchange compounds do not exceed the MPC adopted for black earth soils. Prolonged irrigation does not lead to contamination of leached Ni chernozem, but the soils and irrigation waters need constant monitoring.

heavy metals, biogeochemical features of nickel, gross nickel content, nickel exchange forms, motility percentage, transformation of chernozem, maximum permissible concentrations