Abstract <p>The most readily accessible species of heavy metals (Cu, Zn, Pb, and Cd) in terms of biological availability were isolated from soil samples collected in the impact zone of the Karabash Copper Smelter using the flow extraction method. Leaching of the exchangeable/water-soluble and acid-soluble species of the elements was carried out in a flow-through mode in a microcolumn using aqueous solutions of 0.05 M Ca(NO₃)₂ and 0.43 M CH₃COOH, respectively. The concentrations of elements in the resulting solutions were determined by atomic emission spectrometry. The concentrations of bioavailable species of copper and zinc in the collected soil samples reached 70% of the total content, and it was higher than the MPC values by factors of tens and hundreds (depending on the sampling depth). In most cases, copper was characterized by the predominance of acid-soluble species, while zinc was characterized by the predominance of an exchange species. Cadmium was present in soils only in an exchangeable species (up to 58%) at the most contaminated sampling site. The concentration of lead in biologically available species exceeded the MPC values by a factor of 5–15 and amounted to 10–30% of the total content. Lead in this form was found only at a depth of no more than 10 cm.</p>