Soil samples (77) were collected in October 2009 at a depth of 0-10 cm from the following recreational parks within the city of Poznań Marcinkowski Recreational Park – MRP (18), Wodziczko Recreational Park – WRP (16), Solacki Recreational Park – SRP (26), and Park/Reserve Zurawiniec – PRZ (17). The following physical and chemical soil analyses were performed: particle size, organic carbon, pH, electrical conductivity, and cation exchange capacity. Furthermore, pseudo total amounts of Pb, Cd, Cu, and Zn were extracted by 6 moles HCl dm-3. Bioavailable forms were assayed using the physiologically based extraction test (PBET). On the basis of metal concentrations, potential intakes by children and adults were calculated and risk assessment models elaborated.
Results showed that investigated city parks (MRP, WRP and SRP) exhibited a high capacity to potentially mitigate the mobility of contaminants (pH: 7.1-7.3, CEC 12.0-21.1 cmol₍₊₎·kg^-1) as compared to PRZ (pH_CaCl2 =5.6) and both silt and clay (320 kg^-1), characterized by practically weak buffering properties. The concentrations of all metals exceeded background levels by factors varying, as follows: Cd 6-14; Pb 2-6; Cu 2-3; and Zn 1-4-fold. This enrichment was observed even in the case of the PRZ site, the least anthropogenically impacted. Potential metal intakes by children (particularly) and adults, in cases of accidental swallowing, exhibited the quantitative pattern: Zn > Pb > Cu > Cd, irrespective of investigated parks. Amounts of metal intakes were higher for children, with 94% as compared to 6%, for adults with the following contribution of parks: MRP (42%) > WRP (27%) > SRP (21%) > PRZ (10%). Risk assessment models generated coefficients of determination (R²) varying from 0.57 to 0.81 with a sequence: Zn > Cd > Cu > Pb, which implies that 81, 67, 65, and 57% of respective potential metal intakes can be basically predicted by the knowledge of the level of bioavailable metals fractions.