Study of environmental risks at an old spoil dump field

This environmental case study presents the results of a risk assessment at the deposit in Lubietova, Slovakia. The risks of heavy metals in the studied location are mainly influenced by acid mine drainage (AMD) and natural sorbents presented, i.e. clay minerals (illite, muscovite, smectite, kaolinite, and chlorite), which were identified by x-ray diffraction analysis and create a natural geochemical barrier against their release into ground and surface water. Calculations of the potential for AMD formation show the minimum risks of a dump field to the environment. Seasonal monitoring of ground and surface water contamination by heavy metals and by other inorganic anions (Cl¯, SO₄ ²⁻, NO₃¯, NO₂¯, PO₄ ³⁻) during March 2008-March 2010 proved the aforementioned facts. Content of Cu in drainage and surface water was increased at the Lubietova-Podlipa deposit. The connection with saturation of natural sorbents with copper also was verified by a study of their sorption properties. Utilization possibilities of natural bentonites and zeolites as sorbents for decreasing Cu content in drainage water were studied as well. Their efficiency was approximately 88- 98%. Content of As (As(III):As(V) is 1:5) was not regularly increased in the drainage and surface water in the Lubietova – Svatodusna valley deposit. Nevertheless, it requires regular monitoring.