ABSTRACT
The underground uranium mine Königstein (Saxony, Germany), currently in the process of remediation, represents an underground acid mine drainage (AMD) environment, that is, low pH conditions and high concentrations of heavy metals including uranium, in which eye-catching biofilm formations were observed. During active uranium mining from 1984 to 1990, technical leaching with sulphuric acid was applied underground on-site resulting in a change of the underground mine environment and initiated the formation of AMD and also the growth of AMD-related copious biofilms. Biofilms grow underground in the mine galleries in a depth of 250 m (50 m above sea level) either as stalactite-like slime communities or as acid streamers in the drainage channels. The eukaryotic diversity of these biofilms was analyzed by microscopic investigations and by molecular methods, that is, 18S rDNA PCR, cloning, and sequencing. The biofilm communities of the Königstein environment showed a low eukaryotic biodiversity and consisted of a variety of groups belonging to nine major taxa: ciliates, flagellates, amoebae, heterolobosea, fungi, apicomplexa, stramenopiles, rotifers and arthropoda, and a large number of uncultured eukaryotes, denoted as acidotolerant eukaryotic cluster (AEC). In Königstein, the flagellates Bodo saltans, the stramenopiles Diplophrys archeri, and the phylum of rotifers, class Bdelloidea, were detected for the first time in an AMD environment characterized by high concentrations of uranium. This study shows that not only bacteria and archaea may live in radioactive contaminated environments, but also species of eukaryotes, clearly indicating their potential influence on carbon cycling and metal immobilization within AMD-affected environment.
ABSTRACT
Mine water in the former uranium mine of Königstein (Saxony, Germany) contains high concentrations of acid, sulfate, iron, aluminum, various heavy metals, radionuclides, and nitroaromatics. Research has been conducted for several years to establish the extent to which reduction of pollutant concentrations can be positively influenced and accelerated by storage of reactive materials in mine cavities. Investigations were made at different scales to test and select materials with respect to maximum fixation of contaminants (underground column tests) to examine hydraulic effects (underground large-scale column tests) and to optimize material properties (laboratory tests). The investigations have shown that a mixture of Fe chips and lignitic coal is capable of efficiently cleaning acid and contaminant-containing mine water. The examined material is easily available and compatible with the environment. A large-scale application of such a reactive barrier is being considered for mine water treatment in the future and is deemed to be a reasonable conception for a safety component after conclusion of the flooding.
