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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.

Remediation of areas contaminated by potentially toxic elements (PTE) requires the appropriate assessment of the environmental mobility of contaminants. The fractionation techniques developed for agrochemical and environmental purposes model the pathways of environmental mobilization mainly by sequential extraction procedures. In Europe mostly the simplified extraction scheme proposed by Community Bureau of Reference (BCR) in 1993 is widely used, why only to this certified sediment sample (BCR 701) is available, certified for fractionation of six elements (Cu, Cd, Cr, Ni, Pb, Zn). In the BCR extracts the reagentsolvents applied in leaching steps cause strong matrix interferences when for determination the PTE-contents of these solutions the multielemental capacity of inductively coupled plasma optical emission spectrometry (ICP-OES) should be utilized. Due to the different source of contamination the flexible multi-elemental ICP-OES method should be applied for analysis of the different BCR-extractant-solvent media which makes possible the reliable detection of all occurring PTE in the area. For this purpose as the most adequate solution the application of ICP-OES spectrometer with charge-coupled device (CCD)-detection was selected which is able to record the entire spectral range between 120-800 nm. On the basis of detailed study of BCR-solvent-matrix-and expected-analite-line interferences it was established that the sensitivities of the prominent lines of pollutant elements strongly depend on the type of extractants. For improving the accuracy of analytical results obtained for soils and environmental sediments, matrix matched calibration, internal standardization and robust plasma conditions were recommended and optimized. The successful application of this methodology is presented for a PTE-contamited lake sediment sample and for selected typical Hungarian soil samples stored in sample bank of Hungarian Soil Protection Information and Monitoring System.

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