Mobility of Potentially Toxic Elements from the Abandoned Uranium Mine’s Spoil Bank

This study is part of the ongoing environmental monitoring program of the abandoned Mecsek uranium mine during the remediation period. During this program on the recultivated No.1 spoil bank, the radioactivity and the potentially toxic element (PTE) contents in the covering soil had shown some anomalies which refers to possible migration alongside the slope. Therefore, in a previous study, soil and plant samples were collected from top to bottom position of the slope and the total element content was determined by multi-elemental inductively coupled plasma-optical emission spectrometry. The results have indicated that there was a high possibility for PTEs to be mobile and available for uptake by plants. To confirm this indication in the present study for the soil samples the BCR sequential extraction procedure was applied to characterise the environmental mobility of PTEs, and it was compared with soil pH and cation exchange capacity (CEC). The results indicated that the ratio of Cd, Co, Mn, Pb, and U in the non-residual fractions ranged between 36.8 to 100 % and increased from top to bottom direction. The comparison showed that the samples with the lowest pH and CEC had the most mobility of the PTEs. The distribution of U, Cd, Mn, Co, and Pb in fractions indicated that some parts of the spoil deposit require additional steps to hinder the migration through the covering soil layer, and the BCR sequential extraction procedure has proven to be useful in providing information for the planning and management of remediation operations.