A Study on the Possible Relationship between Physico-Chemical Properties of the Covering Soil and the Mobility of Radionuclides and Potentially Toxic Elements in a Recultivated Spoil Bank

This study is part of the ongoing environmental monitoring program of the abandoned Mecsek uranium mine. On the mine’s recultivated spoil deposit No. I, anomalies that refer to possible migration alongside the slope were detected. The present study was conducted to supplement the ongoing monitoring study with a sampling strategy and analytical methods that can characterize the mobility of potentially toxic elements and radionuclides. A sampling strategy was developed: the vegetation and soil core samples were collected from the slope from top to bottom of the deposit, and nearby this spoil deposit, water samples were collected. Elemental analyses were conducted: the pseudo-total analysis, a total concentration of uranium in water, and the BCR sequential extraction analysis. The radionuclides were determined by gamma spectrometry and alphaGUARD. Additionally, the soil and plant moisture content, soil organic matter, pH, and cation exchange capacity (CEC) were determined. The Pearson correlation analysis and the principal component analysis, considering all possible influencing factors, verified that the elemental concentration increase from the top to the bottom direction of the deposit is strongly influenced by the soil pH, CEC, and Ca content. The mobility of Cd, Co, Mn, Pb, and U is relatively high and significantly migrates down the slope