Behavior and Transformation of Nitrogen Compounds in the Soil-Ground Water System Within the Agricultural Landscapes of Western Siberia

Abstract

Purpose. The article considers the migration and transformation of nitrogen compounds in the soil-groundwater system within the agricultural landscapes of the Tomsk district (Tomsk region, Russia). Materials and methods. The studies were conducted based on the analysis of the chemical and microbiological composition of the ground-water and soil samples and the isotopic composition of nitrate ion dissolved in ground-water. The chemical composition of ground-water and soils was determined by titrimetry, potentiometry, flame photometry, photocolorimetry, fluorimetry, and high-temperature catalytic oxidation. Microbiological analysis of the groundwater and soil samples was carried out by bacterial cultivation on nutrient media for microorganisms related to the nitrogen cycle. The isotopic composition of nitrate ion was analyzed by bacterial denitrification using an isotope ratio mass spectrometer with a trace gas module. The geochemical data obtained were processed using mathematical statistics. Results. The research allowed identifying the processes affected nitrogen compound transformation during an agricultural season and determining their localization in the soil-groundwater system, including the influence of microflora on the transformation of nitrogen compounds. The studies also revealed the relationships between aquifer's geochemical conditions and processes occurring in soil.