Soil samples from playgrounds of 13 kindergartens from Celje municipality were analyzed for pedological properties (pH, CaCO3, organic matter and texture). The amounts of contaminants of potentially toxic metals (PTMs) (Pb, Zn and Cd) were determined. To establish the oral bioaccessibility of potentially toxic metals (PTMs) in humans, in-vitro Unified BARGE Method (UBM) was performed, simulating the gastrointestinal track and in-vitro Standard Operating Procedure (SOP), simulating only the stomach. The PTMs were determined with Flame Atomic Absorption Spectrometer (FAAS). Possible concentration of Pb in the blood of a 3-year-old was calculated with the Integrated Exposure Uptake Biokinetic Model (IEUBK model). In order to reduce the total and bioavailable concentrations of PTMs in the soil, we used six different remediation methods. First method was washing the soil with chelating agent (100 mM CaEDTA) with extraction time of 24 h. Second remediation method was washing with (100 mM CaEDTA) with prolonged extraction time of 72 h. Third method was washing the soil with (3 M HCl) with extraction time of 2 h. The forth method was physical separation of soil fines with wet sieving through 45 µm sieve. The fifth method was stabilization of PTMs with 1 % hydroxyapatite. The sixth method was combination of soil washing with 100 mM CaEDTA (for 72 h extraction time) and stabilization with 1 % hydroxyapatite. After treatment, the soil samples were acid digested and analyzed for PTMs using FAAS. The total quantity of removed PTMs was calculated, and in-vitro bioaccessibility of PTMs in the remediated soils was determined using UBM and SOP. The success of each method was dependent on soil type. Regarding conservation of soil structure, not decreasing pH, eco-friendliness, not loosing big amounts of soil and economy was the most suitable method soil washing with 100 mM CaEDTA.
|
