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 O
/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.
Paradana is one of the biggest ice caves in Slovenia, with an estimated ice volume of 8,000 m
. Reflecting climatological conditions, the cave ice undergoes repeated freeze-thaw cycles and regular ...yearly deposition of fresh ice. Three distinct ice block samples, collected from the frozen lake in May 2016, were analysed to obtain data on ice physicochemical properties and the composition of associated microbiota. Isotopic composition of the ice samples (
O,
H) and a local meteoric water line (LMWL) constructed for monthly precipitation at Postojna were used to estimate the isotopic composition of the water that formed the ice, which had high values of deuterium excess and low concentrations of chloride, sulphate and nitrate. The values of total organic carbon (1.93-3.95 mg/l) within the ice blocks fall within the range of those measured in karst streams. Total cell count in the ice was high and the proportion of cell viability increased along the depth gradient and ranged from 4.67 × 10
to 1.52 × 10
cells/ml and from 51.0 to 85.4%, respectively. Proteobacteria represented the core of the cave-ice microbiome (55.9-79.1%), and probably play an essential role in this ecosystem. Actinobacteria was the second most abundant phylum (12.0-31.4%), followed in abundance by Bacteroidetes (2.8-4.3%). Ice phylotypes recorded amounted to 442 genera, but only 43 genera had abundances greater than 0.5%. Most abundant were Pseudomonas, a well-known ice dweller, and Lysobacter, which previously was not reported in this context. Finally, two xanthophytes, Chloridella glacialis and Ellipsoidion perminimum, known from polar environments, were cultured from the ice. This indicates that the abundance and ecological role of phototrophs in such environments might be greater than previously deduced.
This study presents an example of blackwater (0.8 L flush water, faeces, urine and toilet paper) composting from low-flush vacuum toilets, which is a part of a pilot-scale source separation system at ...a remote tourist facility. Blackwater (BW) was collected from vacuum toilets into a tank and applied over peat filters for particle retention and dewatering on the gravity principle to obtain a solid fraction (SF). Before composting, SF was mixed with pine bark and wheat bran. With no mixing, the thermophilic phase was achieved only in the middle layer and lasted for three weeks. Sanitation was indicated by the inactivation of enterobacterial pathogens, the absence of parasites, and the cessation of phytotoxicity (cress seed germination index ≥80%). High temperatures and high levels of NH4+ in the collecting tank, the peat filters and six weeks of SF composting are plausible reasons for the reduction of pathogens. At the end of composting, the NH4+–N/NO3−–N mass ratio was between 0.5 and 3.0, which indicates mature compost that is ready for use in agriculture. In terms of the percentage of dry matter, the nutrients were nitrogen: phosphorus: potassium = 3.0:3.2:1.6, with a favourable ratio of C:N = 10, indicating the biological stability of the produced compost. The tested pilot-scale model has thus proved that the composting of SF is a viable option as a part of the separation system.
•Blackwater from a source separating treatment system was composted.•Blackwater was composted with sphagnum peat, bark and wheat bran.•The system set-up enhanced the blackwater composting and accumulation of nutrients.•Compost was free of enterobacterial pathogens and indicated parasites inactivation.•Blackwater can serve as additional source of nutrients for agricultural purposes.
Predicting variations in dissolved oxygen concentration (DO) is important for management and environmental monitoring of aquatic ecosystems. Regression analyses and univariate and multivariate ...time-series analyses based on autoregressive methods were performed to investigate oxygen conditions in the Pivka River, Slovenia. The monitoring site was established upstream where the river sinks into the karst cave Postojnska jama, which hosts one of the richest subterranean faunas yet studied worldwide. It was found that abnormal variations of DO started to be noticeable at values of DO < 3 mg/L and became more pronounced until the ecosystem reached fully anoxic conditions. The abnormal fluctuations during the critical summer period were due to environmental conditions, organic load and resident biota. Predictions for future detection of anomalies in DO values were made from stable residuals of the measured data, and it was demonstrated that the model could be used to obtain a reliable estimate for a short period, such as one day. The example presented an analysis pipeline based on specific and established threshold DO values, and it is particularly important for ecosystems with diversity hotspots where prolonged low DO values can pose a threat to their biota.
A commercially available adenosine triphosphate (ATP) detection system (Hygiena, USA), supported by cultivable microbial indicators, was used to estimate bioburden in different habitats in and ...outside show caves: air, water and solid surfaces. A strong positive correlation between ATP concentration expressed as Relative Light Units (RLU) and Colony-Forming-Units (CFU) was observed for swab samples from cave surfaces. In terms of ATP units, surfaces in a single cave system (Postojna Cave) varied considerably (240-1,258,800 RLU/ 20 cm^sup 2^) and commonly exceeded the bioburden level of analogues on the surface (0-114,390 RLU/ 20 cm^sup 2^). Cave sub-habitats were colonized by physiologically distinct microbial communities in terms of their nutrient demands, temperature requirements and r/K growth strategy. The highest ATP biomass indicator (1,258,800 RLU/ 20 cm^sup 2^) for the speleothem that had been touched but accompanied with comparable concentration of CFU (~10^sup 6^ CFU/ 20 cm^sup 2^) for other cave sub-habitats, can be related to the presence of deposited human epithelium skin cells. Show cave infrastructures containing heavy metals, e.g. copper used in safety fences, reduce the viability of microbiota. Mass cave visitation and the presence of allochthonous organic matter result in high levels of airborne and total biomass. Once such material becomes airborne, the location of its settling depends upon natural and human-induced air movements. Underground habitats play an important role in the preservation and concentration of microbial biomass using air and water as transport mechanisms.
(1) Background: Airborne microbes are an integral part of a cave ecosystem. Cave allochtonous airborne microbiota, which occurs mainly during aerosolization from an underground river, from animals, ...and from visitors, is particularly pronounced in show caves. The impacts of tourists and natural river aerosolization on the cave air were estimated in large cave spaces within the Škocjan Caves; (2) Methods: Simultaneously with the measurements of atmospheric parameters, cultivable airborne bacteria were impacted, counted and identified using MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry); (3) Results: A mix of bacteria typically associated with humans and with natural habitats, including a large percentage of non-identified isolates, was found in the cave air. Few of the isolates were attributed to Risk Group 2. A strong positive correlation between tourist numbers and the rise in the concentration of airborne bacteria was indicated. Concentration of airborne bacteria rises to particularly high levels close to the underground river during periods of high discharge. A 10-times lower discharge reflected an approximately 20-times lower concentration of airborne bacteria; (4) Conclusions: Caves that are open and visited contain a diverse airborne microbiota originating from different sources. Enormous cave chambers that display relatively dynamic cave climate conditions do not normally support the enhancement of airborne bacterial concentrations.
During long periods with no precipitation, a sulfidic spring (Smrdljivec) appears in the dry bed of the Reka River before sinking into the karst underground. The study characterizes the area’s ...geological setting, development of microbial communities and an ecotone, and impact on the vulnerable karst ecosystem. Geological mapping of the area, stable isotopic analyses, field measurements, and physico-chemical and toxicity analyses were applied to elucidate the environmental conditions. The spring’s microbial diversity was assessed using cultivation methods, microscopy, and metagenomics. Sulfur compounds in the spring probably originate from coal layers in the vicinity. Metagenomic analyses revealed 175 distinct operational taxonomic units in spring water and biofilms. Proteobacteria predominated in developed biofilms, and a “core” microbiome was represented by methylotrophs, including Methylobacter, Methylomonas, and Methylotenera. Diatoms represented an important component of biofilm biomass. A combination of environmental factors and climatic conditions allows the formation and accessibility of emerging biodiversity hotspots and ecotones. Details of their dynamic nature, global impact, and distribution should be highlighted further and given more protection.
Here is a comprehensive overview of iron's potential in low-carbon energy technologies, exploring applications like metal fuel combustion, iron-based batteries, and energy-carrier cycles, as well as ...sustainable approaches for production and recycling with a focus on reducing environmental impact. Iron, with its abundance, safety, and electrochemical characteristics, is a promising material to contribute to a decarbonized future. This paper discusses the advancements and challenges in iron-based energy storage technologies and sustainable iron production methods. Various innovative approaches are explored as energy storage solutions based on iron, like advancements in thermochemical Fe-Cl cycles highlight the potential of iron chloride electrochemical cycles for long-term high-capacity energy storage technology. Additionally, the utilization of iron as a circular fuel in industrial processes demonstrates its potential in large-scale thermal energy generation. Sustainable iron production methods, such as electrolysis of iron chloride or oxide and deep eutectic solvent extraction, are investigated to reduce the carbon footprint in the iron and steel industry. These findings also show the importance of policy and technology improvements that are vital for the widespread use and recycling of iron-based tech, stressing the need for collaboration toward a sustainable future.
This overview highlights iron's potential in low-carbon energy, including metal fuel combustion, iron-based batteries, and energy-carrier cycles. It also covers sustainable production and recycling methods aimed at minimizing environmental impact.
Biofilms of different colours that colonize surfaces within karst caves represent a source of nutrients. Yellow microbial biofilms were sampled from three caves in southwestern Slovenia, Dimnice, ...Krizna jama and Sveta jama. The highest concentration of cultivable microbes and the biggest number of identified bacteria were retrieved from a sample from Sveta jama. Using Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight for bacterial identification showed that different species of Pseudomonas prevailed in all samples. Yellow biofilms showed an absorption peak around 400 nm, and two emission peaks, a major in the blue and a minor in the orange parts of the spectrum when excited at 405 nm. Microbial mats that colonize surfaces are probably frequently overlooked in caves because they are difficult to observe when they have no pigmentation and the contrast with their surroundings is low. Additional studies are needed to aid the understanding of the role of pigmented biofilms and their interactions with underlying substrata in respect of the evolution of substrate micromorphology.
This study discusses the influence of six bulking materials (peat, bark, oat husks, sawdust, food waste, and wheat bran) on the composting of blackwater solids (feces, urine and toilet paper) from ...low flush vacuum toilets (0.8 L/flush). The focus was on faecal indicator reduction, nutrient recycling, and carbon dioxide and methane emissions. In a composting experiment lasting 60 days, bulking materials were combined and mixed with blackwater solids, composted without stirring and with controlled aeration in a bench scale experiment. The bulking materials combination of oat husks, wheat bran and bark and of oat husks and wheat bran composted with blackwater solids showed the best results in terms of faecal indicator reduction (2.8 log10 reduction of Escherichia coli and 3.2 log10 reduction of faecal streptococci, respectively). Oat husks, bark and wheat bran combination had the smallest nutrient losses of 7.5% total nitrogen, 3.8% total phosphorus and 28% total potassium, while the highest accumulation in total phosphorus was 76.4% occurred in the mixture with oat husks and wheat bran. Peat and food waste improved the sorption of ammonia. The highest methane emissions (average 15.4%) were detected after 28 days of composting in the mixture with bran and food waste. Methane and carbon dioxide levels decreased in all the mixtures towards the end of composting indicating high organic matter degradation. Our findings show that a variety of natural and inexpensive materials can be used and adapted when composing blackwater in remote and sensitive areas.
Display omitted
•Blackwater from vacuum toilets was dewatered in a sequential filter system.•Blackwater solids were mixed with six bulk materials and composted without stirring.•Pathogens and greenhouse gases were reduced, nutrients were recycled.•Oat husks, wheat bran and bark mixture reduced E. coli in mesophilic conditions.•Optimizing blackwater solids compost mixtures contribute to improved sanitation.
PDF
