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This study focuses on the meteorological parameters of the near atmosphere, the surface of the Earth and karst areas, such as temperature of water and air, relative humidity, and wind speed. These parameters are significantly influenced by solar activity, which in turn affects the temperature distribution in karst underground cavities, specifically in the “Kolkina Dupka” cave located within the Ponor Mountain of the Western Balkan Mountains range in Bulgaria. This is the deepest and longest cave in Bulgaria with a length of more than 20 km and a calculated depth of 800 m. Meteorological data within the cave was collected using data loggers, while surface weather data was sourced from National Institute of Meteorology and Hydrology of Bulgaria. Solar activity information was obtained from the website of the Royal Observatory of Belgium. The impact of solar activity on karst regions is substantial and affects temperature, precipitation, and atmospheric circulation. Changes in solar radiation can alter heat absorption on the surface of the Earth, leading to shifts in temperature and precipitation patterns. We performed statistical analysis and modeling to understand the complex interactions between Earth's near atmosphere, the karst system of the Kolkina Dupka cave, and the role of air and water flows in regulating cave temperatures. Results showed a significant negative correlation between air temperatures in the deep underground airflows (at a depth of 130 m below the surface) and temperatures at the cave entrance (at a depth of 40 m during the winter months. Conversely, during spring and summer, an intriguing reversal occurs where higher external temperatures are linked to increased air temperatures at the cave entrance, accompanied by lower temperatures in the deeper zone. Furthermore, by employing “lagged correlations” in result analysis, investigating correlations between internal temperatures and external temperatures over the preceding and subsequent seven days, cyclic variations in heat exchange between the near-surface atmospheric layer and the underground temperatures within the karst system were observed. Specifically, a consistent temperature elevation was noted at the cave entrance three days prior to an increase in external temperatures during the spring-summer season. This temporal relationship was also observed in the solar activity data, where an increase in temperature at a depth of -40 m was registered three days prior to the escalation of solar activity within the measured range of 2800 MHz. The obtained results formed the basis for the development of new theories in solar-terrestrial physics. In summary, there is a connection between solar activity and Earth's climate, but it is not a direct and simple correlation, and it is just one piece of the larger puzzle that shapes temperature variations of the Earth. Climate science involves studying these interactions over extended periods to gain a more comprehensive understanding of the climate system of the Earth.

Lamalunga Cave (Altamura, Southern Italy) is renowned for the discovery in 1993 of an excellently preserved Neanderthal skeleton. Given the importance of the findings and the potential use of Lamalunga speleothems for paleoclimate reconstructions, a detailed monitoring program was undertaken to investigate the connections between microclimate parameters and speleothem growth. The cave air temperature is characterized by annual sinusoidal cycles with increasing phase shift and decreasing thermal amplitude from ± 2.1°C to ± 0.04°C as a function of increasing rock overburden, and daily to sub-daily cycles induced by surface air pressure (SAP) variations characterized by strong 24-hour and 12-hour solar harmonic frequencies, with thermal amplitude decreasing from 0.0054°C to 0.0021°C in the deeper parts of the cave. The ventilation regime is mainly controlled by SAP fluctuations. Fast SAP rises can trigger "emptying events" during which most of the cave air is replaced and the CO2 concentration falls towards near-atmospheric values. The steady and gentle ventilation created by SAP fluctuations also influences the growth and morphology of calcite coralloids, with larger popcorn assemblages concentrated in the northern galleries and delicate branching morphologies prevailing along the South Gallery where stable temperature and relative humidity conditions occur. The study is a seminal example of how high-precision measurements of cave air temperature can provide a wealth of information on cave ventilation and thermal regime and provide valuable support for robust paleoclimate reconstruction from speleothems. [ABSTRACT FROM AUTHOR]

This study focuses on the meteorological parameters of the near atmosphere, the surface of the Earth and karst areas, such as temperature of water and air, relative humidity, and wind speed. These parameters are significantly influenced by solar activity, which in turn affects the temperature distribution in karst underground cavities, specifically in the "Kolkina Dupka" cave located within the Ponor Mountain of the Western Balkan Mountains range in Bulgaria. This is the deepest and longest cave in Bulgaria with a length of more than 20 km and a calculated depth of 800 m. Meteorological data within the cave was collected using data loggers, while surface weather data was sourced from National Institute of Meteorology and Hydrology of Bulgaria. Solar activity information was obtained from the website of the Royal Observatory of Belgium. The impact of solar activity on karst regions is substantial and affects temperature, precipitation, and atmospheric circulation. Changes in solar radiation can alter heat absorption on the surface of the Earth, leading to shifts in temperature and precipitation patterns. We performed statistical analysis and modeling to understand the complex interactions between Earth's near atmosphere, the karst system of the Kolkina Dupka cave, and the role of air and water flows in regulating cave temperatures. Results showed a significant negative correlation between air temperatures in the deep underground airflows (at a depth of 130 m below the surface) and temperatures at the cave entrance (at a depth of 40 m during the winter months. Conversely, during spring and summer, an intriguing reversal occurs where higher external temperatures are linked to increased air temperatures at the cave entrance, accompanied by lower temperatures in the deeper zone. Furthermore, by employing "lagged correlations" in result analysis, investigating correlations between internal temperatures and external temperatures over the preceding and subsequent seven days, cyclic variations in heat exchange between the near-surface atmospheric layer and the underground temperatures within the karst system were observed. Specifically, a consistent temperature elevation was noted at the cave entrance three days prior to an increase in external temperatures during the spring-summer season. This temporal relationship was also observed in the solar activity data, where an increase in temperature at a depth of -40 m was registered three days prior to the escalation of solar activity within the measured range of 2800 MHz. The obtained results formed the basis for the development of new theories in solar-terrestrial physics. In summary, there is a connection between solar activity and Earth's climate, but it is not a direct and simple correlation, and it is just one piece of the larger puzzle that shapes temperature variations of the Earth. Climate science involves studying these interactions over extended periods to gain a more comprehensive understanding of the climate system of the Earth. [ABSTRACT FROM AUTHOR]

To systematically analyze the spatiotemporal heterogeneity, diurnal variation characteristics, and influencing factors of karst cave microclimate environments in Mahuang Cave, a cave in the Shuanghe Cave National Geological Park in Guizhou Province, China, was investigated. Monthly monitoring of meteorological and environmental parameters, such as wind speed, air pressure, humidity, and temperature indicators inside the cave and atmospheric temperature and precipitation outside the cave, was conducted from 2019 to 2021, as well as encrypted monitoring in August and December 2019. The results showed that: (1) The meteorological parameters of Mahuang Cave exhibited seasonal characteristics and cyclical interannual variation. Cave wind speed, relative humidity, and temperature were high in summer and autumn and lowest in winter, whereas cave air pressure was high in winter and low in summer. The atmospheric temperature outside the cave was the main controlling factor. (2) On a short time scale, the dewpoint and temperature of Mahuang Cave did not change significantly, and an abrupt change phenomenon occurred mostly around noon. The warm season was more sensitive than the cold season, and the closer to the entrance of the cave, the stronger the response. (3) In terms of spatial distribution, the overall microclimate factors of Mahuang Cave became increasingly stable and entered a constant state with the increasing depth of the cave passage. The related effects of cave morphology and structure, the physical environment of the cave passage, air movement, and groundwater dynamics were important factors leading to an abrupt change phenomenon in cave microclimates. Local meteorological conditions and cave geometry controlled the temporal variability and spatial heterogeneity of the cave microclimate environment. [ABSTRACT FROM AUTHOR]

Waitomo Glowworm Cave is a highly visited cave where the highlight is viewing the bioluminescence display of a large colony of glowworms. Anthropogenic carbon dioxide build-up in the cave is prevented by management of chimney-effect ventilation aided by a network of microclimate sensors. A cave door prevents ventilationunder drying conditions and promotes it when necessary to clear CO2 and when inflowing air has high relative humidity. A COVID-19-related nationwide “lockdown” in New Zealand from March 2020 resulted in neither staff nor visitors being present in the cave for 60 days, and provided an opportunity to assess the natural microclimate of the cave, especially the natural variation in partial pressure of carbon dioxide (pCO2). In addition, comparison to the previous year showed that the presence of people in the cave increased the cave temperatures but the effect was short-lived due to cave ventilation. During the period of lockdown, the daily increase of carbon dioxide partial pressure (pCO2) due to visitors was absent. When the cave door remained sealed, pCO2 varied and tended to lie at levels above that of the external atmosphere (410 ppm). Notably, rain events raised pCO2 by up to 200 ppm (v/v), which appeared to be sourced from both stream water and drip water. These natural CO2 sources rarely reached the levels associated with cave visitation. The results support current management practices that use door control to enhance cave ventilation when people are in the cave or when natural conditions (high stream levels and high drip-water levels) promote CO2 outgassing into the cave. Suppressing ventilation outside of those times reduces the risk of introducing dry air that could desiccate the glowworms.

Waitomo Glowworm Cave is a highly visited cave where the highlight is viewing the bioluminescence display of a large colony of glowworms. The visitation levels result in the build-up of anthropogenic CO2, to the extent that it could cause corrosion of speleothems. The cave experiences chimney-effect ventilation with air flowing either upward or downward through the main cave chambers depending on air density differences between the cave and the outside environment. Lack of airflow leads to CO2 build-up; however, unrestricted airflow can draw in cool, dry air which is harmful to the glowworms. Consequently, airflow is managed by controlling the opening and closing of a door that seals the upper-most entrance, preventing ventilation under drying conditions and promoting ventilation when it is necessary to clear CO2 and when inflowing air has high relative humidity. A network of microclimate sensors in the cave allows prediction and management of the ventilation pattern. Management leads to asymmetric airflow through the year, which has a flow-on effect on cave temperature. Microclimate monitoring supports the current management practices that use door control to enhance cave ventilation when people are in the cave. Suppressing airflow, especially in winter, reduces the introduction of dry air.

Abstract We document white‐nose syndrome (WNS), a lethal disease of bats caused by the fungus Pseudogymnoascus destructans (Pd), and hibernacula microclimate in New Brunswick, Canada. Our study area represents a more northern region than is common for hibernacula microclimate investigations, providing insight as to how WNS may impact bats at higher latitudes. To determine the impact of the March 2011 arrival of Pd in New Brunswick and the role of hibernacula microclimate on overwintering bat mortality, we surveyed bat numbers at hibernacula twice a year from 2009 to 2015. We also collected data from iButton temperature loggers deployed at all sites and data from HOBO temperature and humidity loggers at three sites. Bat species found in New Brunswick hibernacula include Myotis lucifugus (Little Brown Bat) and M. septentrionalis (Northern Long‐eared Bat), with small numbers of Perimyotis subflavus (Tricolored Bat). All known hibernacula in the province were Pd‐positive with WNS‐positive bats by winter 2013. A 99% decrease in the overwintering bat population in New Brunswick was observed between 2011 and 2015. We did not observe P. subflavus during surveys 2013–2015 and the species appears to be extirpated from these sites. Bats did not appear to choose hibernacula based on winter temperatures, but dark zone (zone where no light penetrates) winter temperatures did not differ among our study sites. Winter dark zone temperatures were warmer and less variable than entrance or above ground temperatures. We observed visible Pd growth on hibernating bats in New Brunswick during early winter surveys (November), even though hibernacula temperatures were colder than optimum for in vitro Pd growth. This suggests that cold hibernacula temperatures encountered near the apparent northern range limit for Pd do not sufficiently slow fungal growth to prevent the onset of WNS and associated bat mortality over the winter.

At present, crevice-type caves are investigated mainly by means of geomorphic and geophysical methods. Microclimatic research of this type of caves is underrepresented and is often limited to temperature and humidity measurement only. Yet, microclimatic research of such caves can significantly help in the management and conservation of caves, speleological exploration or analysis of speleothems. Being the first ever research of ventilation within a crevice-type cave, a complex analysis of cave ventilation was performed within the Velká Ondrášova Cave, a crevice-type cave in the Outer Western Carpathians, Czechia. Long-term temperature recording, airflow tracing within the cave, and a total of nine monitoring field sessions (conducted between February and April 2015, in August 2015, and March 2018) provided data on temperature and airflow inside and outside the cave, serving as a basis for an analysis of ventilation rates, airflow routes within the cave, instability of the cave airflow, and the general ventilation mechanism of the cave. Based on the data, the average cave airflow velocity 0.27–0.61 m∙s−1 corresponding to the ventilation rates 540–1,260 m3∙h−1 (~13,000–30,000 m3/day) was estimated as a rough value of the ventilation, given the complex morphology of the cave. The Helmholtz resonator appeared to be an unsuitable model for an explanation of the instability within the cave airflow velocity. A regression analysis of the cave airflow highlighted the temperature gradient as an important predictor explaining almost 80% of the analyzed cave airflow variability. However, statistical testing suggested the outdoor wind to be also a relevant driving force of the cave ventilation, accounting for the active cave airflow regime during summer.

White-nose syndrome (WNS) is a bat disease caused by the fungal pathogen Pseudogymnoascus destructans, which thrives in cold and very humid environments where bats frequently hibernate. Conidia of Pseudogymnoascus species are often documented on bats prior to the onset of WNS, but characterization of high-risk areas defined by microclimate cave conditions have been lacking. Investigating the occurrence of this fungal genus and appropriate environmental conditions to support P. destructans in southwestern U.S. caves is key to understanding the sites most likely to be impacted by WNS. Microclimate conditions in ten caves at El Malpais (ELMA) National Monument in New Mexico, USA were recorded using i-Button data loggers during the winters of 2011–2014 to assess appropriate environmental conditions (temperature and relative humidity) for P. destructans and other Pseudogymnoascus species. Optimal microclimate conditions for P. destructans and other psychrophilic fungi were found in all the caves with at least 50% of the caves identified as high-risk areas. Pseudogymnoascus species were detected in 70% of the caves using culturing methods and PCR, but no soil samples were positive for P. destructans using real-time PCR in soil and guano samples. Pseudogymnoascus destructans has a recognized range of appropriate temperatures and relative humidity for growth and cave microclimate can help define high-risk areas. This study offers resource managers guidance for establishing priority monitoring areas in their bat caves to determine which bat species are at higher risk.

The theoretical basis for describing natural steady-state conditions in caves as well as for their changes in time that follow from the simple advection-diffusion equation, is given. The impacts of visits to caves – direct impacts due to anthropogenic emissions of heat and CO2, as well as indirect ones, such as illumination and possible drafts when opening the door to the cave – are estimated in dependence to the number of visitors and the size of the cave: the size with which the effects of the visits are below the detection threshold is estimated. It is shown that the sources cause linear responses, while the consequences of the exchange with the walls of the cave or with the exterior depend on time exponentially. Characteristic times for linear as well as for exponential responses are roughly estimated.

Recent environmental processes are studied in ʻA’rak Naʻasane Cave at the northern Judean Desert, Israel. The outer zone of the cave is heavily influenced by the outside environment through a large entrance, facilitating entry of air flow, fauna and humans, with minor cave-forming modifications. Conversely, the inner cave sustains humid and warm conditions, favoring modifications by condensation corrosion of convective air flow, associated with deposition of popcorn speleothems at the lower parts of dissolution pockets. The warm humid air of the inner cave may be associated with an underlying thermal water table. Active condensation corrosion is decreasing, possibly because of gradual change in the cave microclimate, associated with falling water table and ventilation. Increasing connection with the surface is indicated by high collapse domes, rare flood invasion, and a large Trident Leaf-nosed bat community which spends the winter within the innermost parts of the cave. Bat guano supports bedrock corrosion and a rich invertebrate fauna, but humans preferred the outer parts of the cave, particularly for refuge during the second Jewish revolt against the Romans. Rare occasions of ancient human entry into the inner cave support this scenario by the small number of artifacts compared with the outer cave. Enigmatic small cairns in the largest inner hall were probably erected during the Intermediate Bronze Age.

We document white‐nose syndrome (WNS), a lethal disease of bats caused by the fungus Pseudogymnoascus destructans (Pd), and hibernacula microclimate in New Brunswick, Canada. Our study area represents a more northern region than is common for hibernacula microclimate investigations, providing insight as to how WNS may impact bats at higher latitudes. To determine the impact of the March 2011 arrival of Pd in New Brunswick and the role of hibernacula microclimate on overwintering bat mortality, we surveyed bat numbers at hibernacula twice a year from 2009 to 2015. We also collected data from iButton temperature loggers deployed at all sites and data from HOBO temperature and humidity loggers at three sites. Bat species found in New Brunswick hibernacula include Myotis lucifugus (Little Brown Bat) and M. septentrionalis (Northern Long‐eared Bat), with small numbers of Perimyotis subflavus (Tricolored Bat). All known hibernacula in the province were Pd‐positive with WNS‐positive bats by winter 2013. A 99% decrease in the overwintering bat population in New Brunswick was observed between 2011 and 2015. We did not observe P. subflavus during surveys 2013–2015 and the species appears to be extirpated from these sites. Bats did not appear to choose hibernacula based on winter temperatures, but dark zone (zone where no light penetrates) winter temperatures did not differ among our study sites. Winter dark zone temperatures were warmer and less variable than entrance or above ground temperatures. We observed visible Pd growth on hibernating bats in New Brunswick during early winter surveys (November), even though hibernacula temperatures were colder than optimum for in vitro Pd growth. This suggests that cold hibernacula temperatures encountered near the apparent northern range limit for Pd do not sufficiently slow fungal growth to prevent the onset of WNS and associated bat mortality over the winter. [ABSTRACT FROM AUTHOR]

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Abstract Caves are buried geological features of great scientific and engineering interest. Based on the well-known thermal inertia of cave settings with respect to the surface, we have tested the use of thermal infrared (TIR) cameras carried by unmanned aerial vehicles (UAVs) to identify and characterize shallow karstic conduits. A pilot area was selected in a limestone rock massif from the Betic Cordillera (Southern Spain). At surface, this area appears as a doline field with several explored shaft entrances. The main and deepest shaft was thermally monitored at different depths, showing two well defined seasonal stages: (i) air and temperature stratification in summer and (ii) upward air flow and temperature homogenization in winter. We carried out UAV surveys at the expected maximum thermal contrast hours, finding out that winter dawns yielded the most distinctive images. These images show new warm air exits (warm spots) apart from the known cave entrances, and emphasize some of the main entrances depicting large warmed areas around them, which, in turn, can be related to shallow voids and conduits in the cave system. Furthermore, TIR images have been georeferenced using a network of identifiable points that can be transferred from visible orthoimages. The resulting TIR orthoimage mosaics have allowed us to define a number of quantitative parameters to characterize the warm spots. The most important of these parameters are: (i) the characteristic temperature, which is the maximum significant temperature of the air escaping from cave openings; (ii) the warmed area, which is the area that appears on the TIR orthoimage with a temperature greater than the surface temperature mode; and (iii) the average temperature weighted to the affected area. The georeferenced TIR orthoimages and the derived parameters are a new and very valuable tool for both speleological exploration and engineering purposes. Highlights • Thermal Infrared imaging obtained by UAV surveys locate hidden shallow karstic conduits • TIR images have been georeferenced using a network of identifiable points. • Quantitative analysis of TIR orthoimages can serve to characterize caves. [ABSTRACT FROM AUTHOR]

Abstract Quaternary palaeo-environmental changes that have taken place in Croatia are likely to be recorded in speleothems – secondary carbonate deposits precipitated in caves. Confident interpretation of well dated speleothem proxy records relies on modern monitoring programs, which we provided in three regionally different caves. Parallel monitoring of the surface and cave air temperature and relative humidity, precipitation and cave drip intensity, as well as stable isotope modification of meteoric and drip water was carried out in order to estimate the most reliable stalagmites for the interpretation of Quaternary landscape history. In all three caves, Nova Grgosova (239 m a.s.l.; T cave = 11.2 °C) in central Croatia, Lokvarka (780 m a.s.l.; T cave = 7.5 °C) in the mountainous part of Croatia, and Modrič (32 m a.s.l.; T cave = 16.6 °C) in coastal Croatia, we selected the parts of the caves where the ambient cave conditions appeared to be appropriate for equilibrium deposition of calcite in terms of constant air temperature (seasonal amplitudes of 0.73, 0.38 and 0.45 °C, respectively) and relative humidity (100%). Both Atlantic and Mediterranean moisture influences were detected in all three caves, but of different intensities. Cave hydrological settings governed by karst aquifer properties were resolved by the comparison of the precipitation intensities and drip site responses to the rain events, and generally, seasonal rainwater isotopic signal was almost completely attenuated, except for one drip site. Such homogenized drip water and stable cave environmental settings give confidence for calcite deposition under equilibrium conditions, especially for Modrič and Nova Grgosova caves where speleothems' inner structures also look promising for potentially quality dating results and stable isotopic profiles. The fracture-flow drip regime of selected drip sites in Lokvarka Cave, and uncompleted homogenization of the water in the epikarst might point to speleothem samples that are unsuitable for resolving multi-annual Quaternary climate changes. This view is supported by the high porosity internal structure of some Lokvarka speleothems, so further monitoring, sampling and the thorough speleothem examination is therefore necessary for adequate interpretations of palaeo-environmental changes. [ABSTRACT FROM AUTHOR]

The condensation/evaporation process is important in caves, especially in tourist caves where there is carbon dioxide enriched air caused by visitors. The cycle of condensation and evaporation of condensate is believed to enhance condensation corrosion. The problem is condensation is difficult to measure. This study addresses the problem and reports on a method for measuring and modelling condensation rates in a limestone cave. Electronic sensors for measuring condensation and evaporation of the condensate as part of a single continuous process of water vapour flux are tested and used to collect 12 months of data. The study site is the Glowworm tourist cave in New Zealand. The work describes an explanatory model of processes leading to condensation using data based on measurements of condensation and evaporation as part of a single continuous process of water vapour flux. The results show that the model works well. However, one of the most important messages from the research reported here is the introduction of the condensation sensor. The results show that condensation in caves can actually be measured and monitored, virtually in real time. In conjunction with the recent developments in data logging equipment, this opens exciting perspectives in cave climate studies, and, more generally, in hydrogeological studies in karst terrains.

Summary On 28th September 2012, more than 150 mm rain fell in just two hours in some points of southeastern Spain, triggering intense flash floods that resulted in the death of ten people and widespread material damage. In the gypsum karst of Sorbas, rainfall intensity reached 33 mm/h. Air temperature monitoring in different levels of Covadura Cave, down to 85 m depth, enabled the effect of this extreme episode on the cave microclimate to be evaluated in real time. The cave air temperature increased by between 0.9 and 4.1 °C as a result of water flow into the cavity and intense mixing of air masses, in addition to the displacement of deeper air masses toward shallower levels produced by fast recharge of the surrounding karst aquifer. The lag between peak rainfall intensity and the highest cave air temperature was 5–6 h, indicating the response time of the karst to this rainfall event. No trends with depth were observed, suggesting that water not only flowed in through the main cave entrance but also through secondary accesses and fractures. Furthermore, the size of the cave passages and the intensity of air turbulence generated by waterfalls in the cave played an important role in producing these temperature differences. Even though the rainfall event lasted 10 h, cave air temperature did not return to pre-flash flood values until more than 20 days later. This indicates that, while waterflow through the cave might stop a few hours after the rainfall event, cave air temperature can be affected over a longer period. This can be explained by slow groundwater level decreasing of the surrounding karst aquifer and latent heat liberation produced by moisture condensation on the cave walls. Our results show how continuous monitoring of air temperature in caves can be a useful tool for evaluating the short-term effects of flash floods in subterranean karst systems. [ABSTRACT FROM AUTHOR]

This study deals with the spatiotemporal dynamics of CO 2 and its isotopic composition (δ 13 C CO 2 ) in the atmosphere of Altamira Cave (northern Spain) over two annual cycles. In general terms, the cavity shows two distinct ventilation modes, acting as a CO 2 reservoir from October to May (recharge stage), while actively exchanging gases with the outside atmosphere between July and September (discharge stage). In recharge mode, the in-cave air shows higher and relatively homogeneous CO 2 values (3332 ± 521 ppm) with lower δ 13 C CO 2 (−23.2 ± 0.4‰). In contrast, during the discharge stage, the CO 2 concentrations are lower and relatively more variable (1383 ± 435 ppm) and accompanied by higher δ 13 C CO 2 (up to −12‰). This seasonal pattern is controlled by the distinct rates of exchange of air masses with the external atmosphere through the annual cycle, as well as by changes in the production of CO 2 in the soil and natural fluctuations in the concentration of dissolved inorganic carbon transported by drip water into the cave. In contrast to the interpretations of previous studies in Altamira Cave, no local air intakes into the deepest cave sections were flagged by our δ 13 C measurements. This finding is also supported by analyses of CO 2 and 222 Rn in air, density of airborne particles and air temperature. In addition, preliminary experiments examining the visitor-produced disturbances on δ 13 C CO 2 were conducted during the various cave ventilation stages to explore the potential use of this parameter as an indicator of anthropic pressure in caves. Our data show that visits (overall stay of 60–85 min; i.e. , 4 people for 20 min) significantly affected δ 13 C CO 2 (up to Δδ 13 C ∼ −2‰) in the Polychrome Hall of Altamira Cave under conditions of low natural CO 2 (discharge stage), whereas it remained almost unaltered under circumstances of high CO 2 concentration (recharge stage). This demonstrates that δ 13 C CO 2 is sensitive to perturbations produced by visitors during certain periods. [ABSTRACT FROM AUTHOR]

This article presents a method used to identify thresholds to tourist carrying capacity of Santana cave ( CCSC ), in Brazil, and their results. The method comprised three steps: the delimitation of the tourist path; the projection of tourist scenarios; and the verification of the scenarios based on a critical atmospheric parameter: the air temperature. The impacts from visitation were up to 1.1 °C and stabilized in 264.1 min, in average. The results were related to the recovery of the critical factor and were compared to the projected scenarios, which were considered as acceptable. Thus, the suggested CCSC was based in groups of 24 visitors with an entrance interval of 30 min in working days and 18 visitors within 20 min in weekends and holidays. The conclusion reinforces the need to understand the tourist carrying capacity as a dynamic tool, not just to limit, but also to improve the tourist visitation. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the rock surface temperature (RST) regime in Kateřinská Cave in the Moravian Karst (Czech Republic, South Moravia) using nondestructive infrared methods. Air temperature monitoring was also included to quantify the dominant factors affecting the RST. Measurements were taken during the period covering January, 2010 to March, 2012. HOBO air temperature sensors with data loggers were placed in front of the cave entrance, in the entrance corridor and on selected sites in the cave interior. An infrared (IR) thermometer was used to measure the surface temperature of the solid rock. The RST in the cave interior during each season was also recorded by IR camera. The average temperature of the rock surface over the two year period was 6.95 °C. The longterm average of the RST was always 0.01 to 0.79 °C lower than the air temperature. The dynamics of the RST are most obvious at the entrance corridor to the cave, with temperature variability up to 17.34 °C. The dynamism of both the RST and air temperature decrease as the distance from the entrance increases. The lowest RST variability (1.19 °C) was detected at a distance of 271-280 meters from the entrance. The differences in the maximum RST in the monitored profile were relative small, ranging from 7.30 to 8.70 °C. Minimum temperatures in the cold season showed a significant difference among themselves. Changes in rock surface and air temperatures are dominantly influenced by air exchange with the external environment, although the RST may be locally influenced on a short-term basis by other factors, such as attendance and biota. Temperature heterogeneous zones over space in Kateřinská Cave with no air flow were located by thermal imaging. It is therefore an area where unknown spaces or exterior access can be expected. [ABSTRACT FROM AUTHOR]

ABSTRACT Radon concentration and cave temperature were studied at two morphologically different locations (the Beautiful Caves- BC and the lowest point- LP) in Postojna Cave (Slovenia). Radon concentration was considered a trace gas for cave ventilation research, where cave temperature was used as a supported microclimatic parameter. The influence of several climatic factors on radon concentration was studied, from which outside air temperature was found to have the highest control over cave ventilation. Measured radon concentration during 1-year period was in the range from 740 to 4000 Bq m−3 at LP, whereas during 2-year period at BC radon concentration experienced two different annual cycles. The change was observed after flood in September 2010. Radon concentration was in the range from 500 to 9000 Bq m−3 in the year 2010 and 500 to 5500 Bq m−3 in the year 2011 and 2012. Temperature was in the range from 9.9 to 10.5 °C and 9.8 to 10.7 °C at BC and BC-1 (the main passage connected to the LP), respectively. Two different ventilation regimes can be distinguished for LP location and for year 2010 at BC, whereas after flood, three ventilation regimes are characteristic for BC location. Significant change of radon emissions was observed after flood. [ABSTRACT FROM AUTHOR]

Abstract: In August 2009 a continuous cave-air temperature monitoring programme was initiated to help improve the understanding of natural microclimate conditions in Predjama Cave one of 10,700 karst caves in Slovenia. Whereas Predjama Castle, which is build partly in the shelter of one of the cave's entrances, is among the most popular and spectacular tourist destinations in Slovenia, Predjama Cave currently attracts fewer visitors. Studies of the cave microclimate are being conducted to help determine the potential impact of increased tourist visits on the natural cave environment. Recently recorded visitor numbers create no notable impact on the natural cave microclimate. However, increased tourist traffic and additional heat generated by proposed electrical installations could elevate air temperature in the cave. Provision of sustainable precautions to minimize such anthropogenic effects on the cave microclimate and cave fauna must be considered in any future planning for the development of Predjama Cave as a show cave. [Copyright &y& Elsevier]

Speleothems have proven to be one of the most reliable terrestrial archives for palaeoclimate research. However, due to the complexity of karst systems, long-term monitoring and high-resolution analyses of the cave atmosphere and water geochemistry have become essential to better constrain the factors that control calcite growth and how geochemical palaeoclimate proxies are encoded into speleothems. While calcite precipitation incorporates the palaeoclimate signals into the speleothem fabric, certain conditions in caves can favour dissolution, which may form hiatuses or even destroy these signals. In extreme cases, in-cave dissolution by dripwater can form cup-shaped features (i.e., corrosion cups), which were the main focus of this study. The study site in Postojna Cave, Slovenia was investigated through cave climate monitoring and drip and cup water sampling, which took place during 2017–2021. We found that the cups are fed by low-calcium drips as the consequence of the thin rock overburden above the cave. Due to the specific configuration of the airflow pathways, the study site accumulates high levels of CO2 (>10,000 ppm), which shifts low-calcium dripwater into undersaturation. This causes dissolution on the rock surfaces and speleothems on the cave floor. The results of this study have broader significance in addressing the suitability of cave environments and speleothems used in paleoclimate research. [ABSTRACT FROM AUTHOR]