Pb, one of the constituents of ammunition, was identified as a contaminant in an ammunition destruction site. The present study aimed to assess Pb adsorption in the horizons of an uncontaminated representative soil profile of the region where the ammunition destruction site is located. Batch test experiments were performed to determine Pb adsorption in soil horizons, using solutions with natural and modified pH. The ISOFIT software was used to select the isotherm model that best fit Pb adsorption in soil horizons. The results showed that the Langmuir model is the best fit, because it presented the lowest corrected Akaike information criterion value. In addition, the graphical analysis indicated a Langmuir-type isotherm. The Langmuir isotherm parameter (Q0) indicated lower Pb adsorption capacity in the surface soil layers when compared with that in the deeper layers. The change in the initial solution pH influenced Pb adsorption, mainly in superficial horizons. Thus, the risk of soil Pb contamination might be more pronounced in the surface soil layers.
Keywords: Adsorption; Isotherm; Pb; Soil.