Characteristics and impact of aged coal ash with slag emplaced in a karst cave: the case of Divaška jama, Slovenia

A mixture of coal bottom ash and slag, with a fraction of fly ash (CAFAS) from steam locomotives, was placed in the cave Divaška jama to delimit and level tourist trails. Emplacement began in 1914 and carried on for several decades. The CAFAS mixed with other cave material gradually changed its structure and appearance. Currently the concentration of some elements in the CAFAS (As, Cu, Hg, Ni, Pb, Zn), and also to a lesser extent in cave sediments (Cr, Cu, Ni), indicates a possibly harmful effect on sediment-associated biota based on ecotoxicological assays. Compared to the cave sediment, the CAFAS contains distinctly different mineral phases and presents a different source of radioactivity. Microbial metabolic activity of CAFAS is low, 0.22 μl O2/gDW h, but higher than that of cave sediment. The present environmental hazards from CAFAS are estimated to be low. Whereas the emplacement of CAFAS was seen initially a long-term solution for waste disposal and management of the cave, it turned out that CAFAS enriches the underground environment with inorganic and organic compounds and disperses pollution into the cave ecosystem. After its removal from the cave, the CAFAS should be investigated thoroughly due to its susceptibility to alteration.

Preliminary Study of Cave Sample Storage Conditions on Fungal Community Diversity

We investigated the effect of varying storage time and storage temperature on fungal species’ isolation as part of a case study of Illinois cave sediment samples. A deeper understanding of cave fungal communities may influence eco-epidemiology studies of emerging or re-emerging cave fungal pathogens. Using culture-dependent techniques, we isolated geophilic fungi from homogeneous cave sediment samples from three Illinois caves. Each sample was stored under five different temperatures ranging from −80 °C to 22 °C. Cave sediment was periodically removed at five different time periods from 48 h to 1 year, serially diluted with distilled water, lawn plated onto two different media, and monitored for fungal colonies. We isolated colonies and confirmed identity through nrDNA sequence similarity. Our results suggest that storage time was more important than storage temperature for the isolation of a wide diversity of geophilic fungal taxa. Importantly, our results show that varying storage conditions will alter both the kind of taxa and abundance of those taxa, suggesting that comparative studies of fungal diversity across studies should employ similar storage conditions. Lastly, future investigations should utilize multiple genetic markers because the fungal barcode region lacked species-level resolution for many isolates within common Illinois geophilic fungal genera.