Selected heavy metals and their behaviour in urban soils versus soil quality standards

Urban soils reveal great diversity in a potential bioavailability of heavy metals. In Zielona Góra urban area, the bioavailability of Cd, Cu, Ni, Pb and Zn ranged from 1.9 to 98.7%, from 0.8 to 93.3%, from 1.3 to 91.3%, from 0.7 to 99.9% and from 0.4 to 98.9%, respectively. At the same time, in the properties of the soils under analysis some complicated correlations were found. Despite high reaction of the soils (on average pH in water is 7.17 and 6.78 in 0.01 M CaCl2) higher plants take up Cd, Pb and Zn in large amounts, namely wild privet takes up 1.62 mg Cdźkg-1 and 242.4 mg Znźkg-1 at the maximum, and small-leaved lime 31.5 mg Pbźkg-1 at the maximum. In the procedure of determining the critical values characteristic of urban environment, an anthropogenic effect on the formation of urban soils, hence on different soil behaviour, mainly potentially high bioavailability of contaminants, has to be taken into account.