MOBILIZATION OF CADMIUM FROM FESTUCA OVINA ROOTS AND ITS DISTRIBUTION BETWEEN OPERATIONAL FRACTIONS IN SOIL

摘要

Festuca ovina (L.) was grown hydroponically on the Hoagland medium supplemented with CdCl, (10 u,g Cd ml"1). Next, the plants were transplanted into pots (100 plants in pots) with uncontaminated soil and incubated under controlled conditions for 12 months. Approximately 420 ug Cd were introduced into 200 g of soil via the plant roots, the released cadmium being distributed between fractions with varying stability and extractability. After 2 months, the pool of Cd exchangeable and bound to Fe and Mn oxides was 16% and 75%, respectively. After the end of the pot cultivation, the content of Cd in these fractions had decreased to 5% and 53%>, respectively. In contrast, the percentage of Cd defined as organically bound increased from 6% (after 2 months)to 43% (after 12 months). The residual fraction was 2% of the metal present in the soil and was constant during plant cultivation. The results obtained indicate that the Cd stabilization by roots was dependent on time. Additionally, the distribution of Cd among the tested fractions was seen to have changed during the experiment. The amount of Cd bound to soil organic matter increased, lowering the amount of the bioavailable Cd form and Cd fraction bound to the oxide minerals.