Assessment of the Concentration of Potentially Contaminating Metals in the Soil Profile of an Area Under the Use of Swine Liquid Waste

Abstract

Abstract Pig farming is a significant economic activity, especially in the Southern states of Brazil. However, it can have environmental impacts, primarily through the discharge of liquid effluents into the soil. Therefore, this study aimed to analyze the variability in the concentration of chemical elements in the soil in two areas located on the same property, one using swine waste and the other without, in the Northwestern region of the Rio Grande do Sul State. To do this, the concentrations of the chemical elements Cadmium, Chromium, Cobalt, Copper, and Zinc were analyzed at three depths (0.00, 0.50, and 1.00 meters) using Flame Atomic Absorption Spectrometry. Physical parameters (particle size distribution and saturated hydraulic conductivity) were also determined. The results indicated that the soil has low permeability, with a predominance of the silt fraction. Regarding the chemical parameter analyses, values above the levels established by current legislation were identified, with Copper and Cadmium showing higher values at all analyzed spots and depths. Significant differences between the areas were observed only at a depth of 1.00 meter and for the elements Zinc, Cobalt, and Manganese. It can be concluded from this that the use of swine liquid waste did not alter the natural properties of the soil, and the higher concentration of Copper may be related to the geological origin of the region. For some chemical elements, leaching through the soil profile and/or translocation of the clay fraction to deeper layers were observed.