Assessing the Impact of Soil Humic Substances, Textural Fractions on the Sorption of Heavy Metals (Cd, Pb)

Abstract

This study examined the sorption of heavy metals in selected soils (e.g., Andosol, Cambisol, Planosol) in Slovakia, focusing on the kind and quantity of humic materials as well as the soil’s characteristics. Heavy metals were detected using GT AAS, while UV-Vis spectroscopy was used to determine humic substances’ colour quotients. The impact of the total organic carbon on the total cadmium, bioavailable lead, and cadmium was highlighted. The results reveal positive correlations among humic substances and bioavailable forms of Cd (r = 0.692) and Pb (r = 0.709). A relationship was discovered between FAs and the bioavailable forms of Pb (r = 0.743) and Cd (r = 0.700) and between the level of HSs and the bioavailable content of Cd (r = 0.499). Bioavailable heavy metals showed a positive correlation with clay fraction and a negative correlation with heavy metal content. Correlations were found between the bioavailable heavy metal forms and the colour quotients of humic substances and humic acids. Heavy metals in bioavailable forms decreased with the levels of the condensation and dispersion of humic substances. From clay to silt, the amounts of Cd and Pb increased. This study’ results provide insights into the relationships between soil properties, humic substances, and the sorption of the studied elements.