Effect of Soil Aggregate Separation Methods on the Occurrence Characteristics of Typical Pollutants

Certain patterns of zinc, copper, and lead redistribution across the structural fractions of Chernozems and Urbic Technosols

The purpose of this work was to study the patterns of Zn, Cu, and Pb distribution in soil aggregates of various size fractions. Materials were Calcic Chernozems and Urbic Technosol of the Rostov agglomeration. Soil samples were passed through sieves with different mesh sizes (dry sieving). For the study, particle size fractions of > 10, 7-5, 5-3, 2-1, and < 0.25 mm were sampled, where the total forms of Zn, Cu, and Pb were examined by means of the X-ray fluorescence method. In the Zn content in both Calcic Chernozems and Urbic Technosol peaks in < 0.25-mm particle size fractions, the concentration decreases as particle size grows. Calcic Chernozems display Cu concentrations in mid-size soil particles of 2-1 and 5-3 mm. In Urbic Technosols, the lowest Cu concentration is typically found in particle size fractions of > 10 mm. Pb in Calcic Chernozems is concentrated in mid-size soil aggregates of 2-1 and 5-3 mm. However, Urbic Technosols tend to accumulate silt-fraction lead (< 0.25 mm). A higher zinc concentration in silt-fraction aggregates found in Urbic Technosols in comparison to Calcic Chernozems highlights the anthropogenic origin of a considerable part of this element's soil pool. Excessively high lead content in UR (urbic) horizons leads to the structure degradation and, consequently, to a transformed overall trend of HM distribution across the soil profile in general.