Mobility and bioaccessibility of risk elements in the area affected by the long-term opencast coal mining

The potential environmental hazards of risk elements in the area affected by the opencast coal mine and/or coal combustion for plants and animals was assessed by using a suite of laboratory bioaccessibility tests. The chosen sampling area was in the vicinity of the largest coal mine spoil in the Sokolov coal basin (Czech Republic). For an estimation of the oral bioaccessibility of the risk elements in soils, the physiologically based extraction tests were applied. Among the available methods for estimating the pulmonary bioaccessibility of elements, the Gamble's and Hatch's tests were chosen. The results showed elevated pseudo-total soil contents of As, Be, Cd, Cu, Pb, V, and Zn. Among these elements, only Cd showed substantial bioaccessibility for plants, as documented by the high Risk Assessment Code, reaching up to 47%, and the highest plant-availability, where the maximum Bioaccumulation Factor in plants reached up to 4.5. The simulated body fluids showed the highest bioaccessibility of Cd, but also substantial bioaccessible pools of As and Be, the elements frequently found at the brown coal mining and processing areas. For better understanding of the risk element bioaccessibility under the specific conditions, the released element pools should be related to the particular soil physicochemical parameters.