The study was aimed at determining the content, distribution and mobility of barium and strontium in various forest podzol soils. Samples with a wide range of chemical and physical properties were collected from typical uncontaminated soils of south-western Poland. The total metal content in the analyzed soils was considered as the geochemical background thanks to the natural features of the study site. Sequential chemical extraction procedure were used to provide information on the mobility and bioavailability of the studied metals in the soil. Fractions of Ba and Sr were determined using the five-step procedure of Tessier et al. (1979). The results show that heavy metals were generally represented by the exchangeable fraction (F1 . barium) and the residual fraction (F5 . strontium) with the average values at 53 and 69%, respectively. The mobility of barium in all soil profiles was very high, ranging within 52.54% and indicating a generally high availability and mobility. Relatively very low levels of the trace elements were found in the fraction bound to organic matter (F4: 3.8%). Very low levels of strontium were found also in the fraction bound to carbonates (F2: 2.3%). Humic-eluvial, illuvial and sideric horizons were enriched in the fractions of barium and strontium bound to iron and manganese oxides (F3).
The article presents several aspects of computer simulations and models of heavy metals speciation in environmental samples. The methods can be effectively used in environmental sciences, soil science, and assessment of mobility and bioavailability of heavy metals in contaminated areas. The article presents all of the methods based on examples, and with interpretation of results. The effect depends on the reliability of data used in models. The results are essential for predicting the fate and behaviour of elements in the environment, and can also be used to develop solubility curves.
The investigation was carried out on forest soils collected from areas subject to variable pollution. The fraction of strontium was analyzed in soil samples from north-eastern Poland (Borki forest division), treated as a non-polluted region (natural background) and in soil samples from central (Rogów forest division) and south-western Poland (Świerklaniec forest division). The sequential extraction procedure was applied in this study to separate the fractions of strontium. Five fractions were analyzed in every genetic horizon according to the Tessier method. The concentration of strontium was also analyzed in the plants. Both results were compared in order to evaluate the mobility and bioavailability of the trace elements in the environment. The content, distribution and bioavailability of the strontium fractions were investigated with particular emphasis on the contaminated study sites. Total content of strontium in surface horizons depended on the localization. Among analysed fractions strontium, in organic soil horizons, regardless of localization, occurred predominantly in mobile fractions in all examined soils.