Technosols or technogenic substrates contaminated by potentially toxic elements as a result of iron mining causes not only contamination of the surrounding ecosystem but may also lead to changes of the extent, abundance, structure and activity of soil microbial community. Microbial biomass were significantly inhibited mainly by exceeding limits of potentially toxic metals as arsenic (in the range of 343–511 mg/kg), copper (in the range of 7980–9227 mg/kg), manganese (in the range of 2417–2670 mg/kg), alkaline and strong alkaline pH conditions and minimal contents of organic nutrients. All of the 14 bacterial isolates, belonged to 4 bacterial phyla, Actinobacteria, Firmicutes; β- and γ-Proteobacteria. Thirteen genera and 20 species of microscopic filamentous fungi were recovered. The most frequently found species belonged to genera Aspergillus (A. clavatus, A. niger, A. flavus, A. versicolor, Aspergillus sp.) with the dominating A. niger in all samples, and Penicillium (P. canescens, P. chrysogenum, P. spinulosum, Penicillium sp.). Fungal plant pathogens occurred in all surface samples. These included Bjerkandera adustata, Bionectria ochloleuca with anamorph state Clonostachys pseudochloleuca, Lewia infectoria, Phoma macrostoma and Rhizoctonia sp.

In the spring 2012, post-flotation tailings of the inactive impoundment Lintich (Slovakia) were sampled. In the impoundment sediment and also in its surrounding, we detected concentration of Pb, Zn, Cd, Cu, and Ba exceeding limiting values. We detected low values of the microbial biomass carbon and microbial activity in the impoundment sediment (LiS) and its dam (DAM) along with potential respiration stayed relatively low and therefore also substrate availability index and metabolic quotient (qCO2) were higher in the control sample (REF) than in the LiS and the DAM. The low qCO2 level indicates that microbial community, despite of dangerously high levels of heavy metals in sediment, is still able to sufficiently utilize sources of available organic carbon. Anyway, we could doubt function of the metabolic index as universal indicator of environment conditions, regarding the anthropogenic substrates. We confirmed changes in composition of the mite communities along gradient dam-impoundment. The percentage of eudominant, recendent, and subrecendent species increased at the expense of dominants and subdominants, all together with decreasing diversity and equitability of the community. We identified species Chamobates borealis, Carabodes rugosior, Metabelba propexa, and Pergalumna nervosa with negative respond under the heavy metal stress. Species Adoristes ovatus was indifferent and Dissorhina sp., Hafenrefferia gilvipes, and Oppiella nova prospered under the loaded conditions. Forty years after experimental afforestation, we expect specific community of actively surviving microorganisms and Oribatida species detected in the DAM are usual in the greatly degraded habitats or on sites in the early succession.

The samples of two technogenic sediments (MOS, coal ash sediment; MOD, a mixture of ash and natural soil) and two natural soils (MOM, meadow; MOF—forest; both Cambisol Dystric) in the vicinage of the coal ash basin were studied. We evaluated risk element concentrations and select-ed chemical and microbiological parameters to determine their influence on the community structure of Oribatida. High concentrations of various toxic elements, alkaline pH, and low hu-midity negatively affected the abundance of oribatid mites. The microbial indicator values showed that the soil microbial community formed in technogenic sediments could effectively use organic carbon. However, considering the wide C/N ratio of the substrates, the process of soil organic matter (SOM) decomposition was slowed down, and thus nutrients were less available for the mites, which could be among the reasons why we did not find any individual of oribatid mite in MOS. In MOD, however, we found representatives of three species, but only Tectocepheus velatus sarekensis established an abundant community at the highly contaminated site. Anthropogenic pressure resulted in the selection of r-strategists, which became dominant and reduced the whole community’s species’ diversity. Therefore, we consider it a suitable indicator of improper human intervention in the ecosystem.

With respect to acidic, cyanide-laced tailings, the data about in situ toxicity and biological activity in highly polluted environment are often lacking. The aim of this study was to assess the microbial characteristics, composition of oribatid mite species, and level of genotoxic impact on plants in the area of inactive tailings pond (Horná Ves, Kremnica region). Sampling of the tailings, soils and selected plant species was carried out in spring of 2012. Trace element analysis (inductively coupled plasma emission and mass spectrometry) showed that concentration of Pb, Zn, and Cu in the tailings is approximately in thousands of ppm (mg kg(-1)). Amount of lead exceeded 16,000 mg kg(-1), which is perceived as the biggest threat with respect to possible toxicity. The risk is accentuated by extremely acidic pH of the tailings material which approached 2. In such conditions great mobility of (divalent) heavy metal cations is expected. The total cyanide concentration in the tailings was 472 mg kg(-1). Results of performed tests and measurements suggest that microbial activity at the tailings site (and its close environment) is hampered markedly. In the sludge material we detected low abundance of soil bacteria (2.08 × 10(4) CFU) and predominance of slowly growing K-strategists. On the other hand, the content of microbial C in the sludge sample was not too low, considering its extreme acidity and high amount of risk elements. In the same sample, just one mite species, Oppiella (O.) uliginosa (Willmann 1919), was identified. Also in case of the dam site the abundance of mites was considerably lower in comparison to reference sample. Values of Oribatida abundance were in positive correlation with values of microbial biomass carbon. Results of the pollen grain abortivity test, applied in situ on chosen plant species, indicated substantial presence of genotoxicity in the environment. Total induction index of tailings pond reached 3.59(±2.4) which expresses also total load of locality, comparing to natural biotope. In case of the technogenic sediment, the value was more than three times higher.