Fluxes of polycyclic aromatic hydrocarbons (PAHs) were investigated along the route of transport in a south German karst system. Atmospheric deposition, seepage water in caves and spring water at the outlet of the catchment were monitored continuously over 1.5 years allowing the establishment of an input/output mass balance at the catchment scale. The results reveal that, even in the highly vulnerable karst catchment, PAHs are effectively retained in the soils. Only during high discharge events, such as snowmelt in spring, increasing PAH concentrations at the outlet of the catchment indicates a mobilization of the pollutants. These events are typically correlated with increasing particle concentrations. Based on our results, we conclude that particle-facilitated transport is the dominating cause of PAH mobilization. In summary, PAHs accumulate over time in soils and only occasionally high discharge events cause a short concentration pulse to be flushed through the karst system.

Environmental pollution is a topic of great interest because it directly affects the quality of ecosystems and of all living organisms at different trophic and systematic levels. Together with the global climate change, the long-term surviving of many species of plants and animals is threaten, distributional patterns at global and regional levels are altered and it results in local assemblages of species that are quite different from those that currently constitute coevolved communities. .For this study, the species Myotis myotis was used as bioindicator and it was sampled from two caves in the south-east of Sicily, Pipistrelli chosen as control area and Palombara chosen as polluted area, to measure the concentrations of trace elements in fur and liver tissues. Results showed higher content of essential elements in fur in bats sampled from Pipistrelli. Conversely, higher concentrations of toxic metals in liver such as As, Cd, Pb and Hg were measured in bat samples in Palombara cave, where specimens have a hunting area extended within the boundaries of the petrochemical plant. Nevertheless, we cannot consider Palombara population as polluted by metal contamination since their tissue concentrations are overall lower than toxic thresholds values suggested for small mammals. Likewise, we cannot exclude other kind of pollutants as potential stressors of the examined population, contributing with the decreasing of bat colonies in Sicily.

Marine caves are unique and vulnerable habitats, threatened by multiple global and local disturbances. Whilst the effects of climate change on marine caves have already been investigated, no information exists about the effects of local human impacts, such as coastal development, on these habitats. This study investigated the impact of the construction of a touristic harbour on two shallow underwater marine caves in the Ligurian Sea (NW Mediterranean). As a standard methodology for monitoring marine caves does not exist yet, changes over time on the benthic community were assessed adopting two different non-taxonomic descriptors: trophic guilds and growth forms. Harbour construction caused an increase of sediment load within the caves, with a consequent decline of filter feeder organisms. Abundance of small organisms, such as encrusting and flattened sponges, was greatly reduced in comparison to organisms with larger and erect growth forms, such as domed mounds and pedunculated sponges. Our study indicated that growth forms and trophic guilds are effective descriptors for evaluating changes over time in marine caves, and could be easily standardised and applied in monitoring plans. In addition, as the harbour construction impacted differently according to the cave topography, the use of a systematic sampling in different zones of an underwater cave is recommended.

Concentrations of naturally occurring radioactive gas can be high in caves and mines, and it has been shown that releases of radon (²²²Rn) to the outside environment through ventilation can be large. We assess airflow and associated activity concentrations of thoron (²²⁰Rn) and progeny (TnP) being released through a drainage pipe from an old mine-complex situated in thorium-rich bedrock. Outdoor thoron concentrations in this area have been thought to arise solely from thoron exhalation from the ground. However, thoron concentrations in outwards airflow in the drainage pipe range from 25 000 Bq m⁻³ to 42 000 Bq m⁻³ and discharges can in summer be as high as 1 GBq d⁻¹. The drainage pipe can be considered as a point source adding to exhalation from the soil and deposits of waste rock in the area. Statistical analyses including meteorological data suggest that outdoor temperature is the main factor affecting this airflow and that ventilation of these mines resembles chimney ventilation, but other weather variables may also contribute. During summer with warm outdoor temperatures, colder and denser air within the mines escapes through the drainage pipe, which is located on low ground. In winter, when outdoor temperatures are lower than those within the mines, the direction of airflow in the drainage pipe is inwards into the mines, while air escapes upwards and outwards through larger mine openings located on higher ground. Statistical outliers indicate Venturi effects by strong winds and syringe effects by internal water level.

Radon concentration and gamma activity concentration of naturally occurring radionuclides were determined and presented for two tourist caves (Karaca and Çal caves) in this study. These caves are reported to receive about 77,000 visitors during the summer season in 2007. It was seen that mean radon activity concentrations for the winter and summer seasons for the Karaca cave is 1,023 and 823 Bq/m³ and for the Çal cave is 264 and 473 Bq/m³. Mean ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations are found to be 43, 19, and 262 Bq/kg for the Karaca cave and 31, 27, and 460 Bq/kg for the Çal cave. Doses received by the cave guides due to radon were estimated to be 2.9 mSv/year for the winter season and 2.3 mSv/year for the summer season for the Karaca cave. Same values were estimated for the Çal cave, and the results were found to be 0.6 mSv/year for the winter season and 1.1 mSv/year for the summer season. Annual effective doses received by the visitors in both caves were estimated to be in the order of μSv/year because of the short exposure time comparing the cave guides. Although the reported values are below the recommended values, both groups are exposed to possible radiological risk during their stay inside the cave, since prolonged exposure to high radon concentration has been linked to lung cancer.

The radiation dose and environmental health risk of radon concentration in the Lantian karst cave of China to guides and visitors were estimated based on the continuous radon concentration monitoring. Distinct seasonal variations were observed in the radon concentration of the air inside the cave. The maximum concentration occurred in the summer, whereas the minimum radon concentration occurred during the winter. The annual average radon concentration in the caves investigated is slightly higher than the upper bound of radon action level for underground space used in China and less than the upper bound of radon action level recommended by the International Commission on Radiation Protection (ICRP) for workplaces. The annual effective dose to tour guides working in two investigated caves varies from 4.1 to 16.5mSv, depending on different equilibrium factors together with different dose conversion factors proposed in the literature. The annual maximum time that a tour guide or other worker can safely be inside the cave is estimated to be 1,250 or 2,246h, depending on whether one bases this on the high or mean radon concentration, with an equilibrium factor of one in both cases. Given the synergistic effects of smoking, tour guides who are smokers should be in the cave only 10-20% of these hours. In all cases, the annual effective doses to visitors are well below the 1mSv maximum suggested dose for a member of the public for 1 year.

Green microalgae colonizing stone surfaces represent a major problem for the conservation of heritage monuments, since they lead to biodegradation and aesthetic issues. Previous studies in La Glacière show cave (France) have demonstrated that UV-C may have a strong effect on microalgae, thus leading to chlorophyll bleaching, which was increased when biofilms were maintained under VIS-light condition unlike to those maintained in the dark. To understand the physiological mechanisms underlying this response and in order to optimize in situ treatment, 30 kJ m⁻² UV-C exposure times were applied to Chlorophyta Chlorella sp. and chlorophyll degradation kinetics were then monitored. UV-C irradiation was enough to inhibit photosynthesis and to directly kill all algal cells. Results also showed that chlorophyll a was degraded faster than chlorophyll b and that 14 h were necessary for complete degradation of all the present chlorophyll. In addition, our results highlighted the importance of visible light exposition after UV-C treatment which leading to chlorophyll bleaching. Irradiated algae cultivated in the dark were still green 5 days after treatment while cultivated samples in the light lost their green color after 14 h. An efficient UV-C treatment applicable to show caves and other heritage monuments was proposed.

The paper presents the varied presence of nitrates and phosphates in water from caves located in Częstochowa and Kraków, in urban, strongly anthropogenic conditions, representing the vadose zone of the fissure-karstic-porous massif of Upper Jurassic limestones. Hydrochemical research was carried out by the authors in the Cave on the Stone in Częstochowa in 2012–2015, in caves of the Zakrzówek horst from 1996 to 2002, and in the Dragon’s Cave by the research team of J. Motyka in 1995–1998. A number of NO₃ and PO₄ measurements were performed in waters sampled at these research sites: 20 measurements each of NO₃ and PO₄ at the Cave on the Stone, 228 of NO₃ and 422 of PO₄ at Zakrzówek, and 19 each of NO₃ and PO₄ at the Dragon’s Cave. To assess the quality aspect of N and P compounds in waters from the Cave on the Stone, the results of geochemical modelling were processed using PHREEQC software. In cave waters, the oxidised form of nitrogen NO₃ ⁻ predominates; in surface waters in the vicinity, unoxidised forms prevail: NH₄₊, NH₃, and NH₄SO₄ ⁻. Among phosphorus speciations, dissolved forms are dominant: HPO₄ ²⁻, H₂PO₄ ⁻, and the insoluble form CaHPO₄; in surface waters, these forms are practically absent. Transformations of water chemistry in ‘urban’ caves, often centuries old, manifest themselves in, inter alia, the occurrence of multi-ionic waters, including seasonal variations and extremely diversified concentrations, with very high concentrations in subpopulations of NO₃ (0.2–485 mg dm⁻³) and P (0.02–6.87 mg dm⁻³). The common presence of NO₃ in waters of the phreatic zone of the Częstochowa Upland, an area developed in an agricultural direction, is documented by, inter alia, the exploitation of intakes supplying the city of Częstochowa (10–57 mg dm⁻³, 2011) and crenological studies from 2008 to 2015 (NO₃, 2–58 mg dm⁻³), at simultaneously low phosphate concentrations (PO₄, 0.02–0.24 mg dm⁻³).

Caves in Mizoram, Northeast India, are potential hotspot diversity regions due to the historical significance of the formation of the Indo-Burman plateau and also because of their unexplored and unknown diversity. High-throughput paired end Illumina sequencing of the V4 region of 16S rRNA was performed to study the bacterial community of three caves situated in Champhai district of Mizoram, Northeast India. A total of 10,643 operational taxonomic units (OTUs) (based on 97 % cutoff) comprising of 21 major and 21 candidate phyla with a sequencing depth of 1,140,013 were found in this study. The overall taxonomic profile obtained by the RDP classifier and Greengenes OTU database revealed high diversity within the bacterial communities. Communities were dominated by Planctomycetes, Actinobacteria, Proteobacteria, Bacteroidetes, and Firmicutes, while members of Archaea were less varied and mostly comprising of Eukaryoarchea. Analysis revealed that Farpuk (CFP) cave sediment has low microbial diversity and is mainly dominated by Actinobacteria (80 % reads), whereas different bacterial communities were found in the caves of Murapuk (CMP) and Lamsialpuk (CLP). Analysis also revealed that a major portion of the identified OTUs was classified under rare biosphere. Importantly, all these caves recorded a high number of unclassified OTUs, which might represent new species. Further analysis with whole genome sequencing is needed to validate the unknown species as well as to determine their functional role.