Influence of pH on the solubility of arsenic in heavily contaminated soils / Wpływ pH na rozpuszczalność arsenu w glebach silnie zanieczyszczonych

The aim of this study was to determine the impact of pH on arsenic solubility in soils heavily contaminated by the former arsenic industry. For the purpose of the study, three soil samples were collected from the area affected by ore processing in Złoty Stok. Soils differed in initial pH, calcium carbonate content, organic matter content and total arsenic concentration. The amounts of arsenic released from soils at various pH were measured using extraction tests, where soil samples were shaken with various doses of HCl and NaOH in the presence of 0.01 mol • dm⁻³ CaCl₂ as the background solution. Arsenic solubility in soils was considerably low at neutral or slightly acidic pH and increased considerably in both strongly acidic and alkaline conditions. The importance of these effects for environmental risk was discussed.