Limitation of Pb and Cd Uptake by Pine

Abstract

Model experiments were carried out using 1-year-old pine plants grown in water cultures with the aim of investigating whether and to what extent the accumulation of Pb and Cd in plants can be decreased through decreasing the nutrient solution concentration, supplementing with forest soil, supplementing with calcium carbonate, and addition of brown coal. It was found that with increased doses of Pb and Cd in water cultures pine plants take up more of those elements. Whereas Pb accumulates mainly in the roots, about half of the Cd is transported to the above-ground part of the plants. Addition of Pb, Cd, and forest soil to the nutrition medium increased Pb uptake by pine plants compared to the control treatment. The effect of soil addition was not that evident in the case of Cd uptake. Furthermore, it was observed that addition of brown coal resulted in a slight increase of Pb accumulation in the shoots and in a considerable decrease of its accumulation in roots. A higher increase of Cd accumulation in the shoots was observed after brown coal was added to the nutrient solution. The amounts of Cd and Pb accumulated in plants, mainly in the shoots, decreased following the addition of CaCO3. When CaCO3 and brown coal were added jointly, this effect was markedly more pronounced. The decrease of nutrient supply (down to one-quarter of the original concentration) increased the content of Pb, especially in the roots; for Cd, changes in its content in pine were not univocal.