Heavy metal accumulation in soils and leaves of Betula pendula in urban pollution conditions

The main aim was to study heavy metal (Cu, Zn, Fe, Mn, Pb, Cd, Ni, Co, Cr) migration in soil-birch (Betula pendula) system, as well as to determine the contribution of metal aerotechnogenic migration to their total accumulation by birch leaves. Soils and birch leaves were sampled near industrial enterprises and transport hubs in Tyumen. The mobile and acid-soluble metal fraction content in soils, as well as metal content in washed and unwashed birch leaves were determined by atomic emission spectroscopy. Metal accumulation in urban soils compared to the control decreased in the order: Cd>Pb>Cr>Ni>Zn>Cu>Fe>Co>Mn. Pb and Ni content exceeded the MPC. Metal accumulation in birch leaves decreased in the order: Pb>Cr>Fe>Co>Cu>Ni>Zn>Mn>Cd. Pb, Zn, Ni, Fe, and Cr content exceeded the MPC. The greatest metal accumulation in soil was at railway station, while in birch leaves – in the vicinity of metallurgical plant. Metal mobility in soil decreased in the order Cd>Pb>Mn>Zn>Ni>Co>Cu>Cr>Fe, which correlated with their bioavailability: Zn>Cd>Mn>Cu>Ni>Pb>Cr>Fe>Co. The contribution of aerotechnogenic metal migration studied by the difference of metal content in washed and unwashed leaves, was 20-30%. Aerotechnogenic migration decreased in the order: Cr>Ni>Cd≈Mn>Fe>Zn≈Pb≈Co>Cu. The correlation between aerotechnogenic migration and metal compounds volatility was established.