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.
The presented studies were focused on evaluating the utility of one of sequential extraction methods for evaluating the bioavailability of mercury in soils polluted by this element. Soil samples collected from horizons 0-20 cm and 20-80 cm were subject to analysis of the basic physical and chemical properties of soils. Moreover, the total content of mercury was determined and sequential extraction of mercury was conducted using a modified five-stage Wallschläger method. The analyses show that the studied soils are characterized by a variable mercury content, the highest in the surface soil horizons. Sequential extraction of mercury in the analyzed soils has indicated that the highest percentage content in the total content had mercury linked with sulphides. A high content of mercury linked with organic matter was also noted. The content of bioavailable mercury did not exceed 1.5% of the total content.