Abstract
A data-driven approach insensitive to the initial conditions was developed to extract governing equations for the concentration of CO
2
in the Altamira cave (Spain) and its two main drivers: ...the outside temperature and the soil moisture. This model was then reformulated in order to use satellite observations and meteorological predictions, as a forcing. The concentration of CO
2
inside the cave was then investigated from 1950 to 2100 under various scenarios. It is found that extreme levels of CO
2
were reached during the period 1950–1972 due to the massive affluence of visitors. It is demonstrated that it is possible to monitor the CO
2
in the cave in real time using satellite information as an external forcing. For the future, it is shown that the maximum values of CO
2
will exceed the levels reached during the 1980s and the 1990s when the CO
2
introduced by the touristic visits, although intentionally reduced, still enhanced considerably the micro corrosion of walls and pigments.
Castañar Cave is a clear example of an oligotrophic ecosystem with high hygrothermal stability both seasonal and interannual and the particularity of registering extraordinary levels of environmental ...radiation. These environmental conditions make the cave an ideal laboratory to evaluate both the responses of the subterranean environment to sudden changes in the matter and energy fluxes with the exterior and also any impact derived from its use as a tourist resource under a very restrictive access regime. In 2008, a fungal outbreak provoked by a vomit contaminated the sediments which were removed and subsequently treated with hydrogen peroxide. Fungal surveys were carried out in 2008 and 2009. The visits were resumed in 2014. Here, 12 years after the outbreak, we present an exhaustive study on the cave sediments in order to know the distribution of the different fungal taxa, as well as the prevalence and spatio-temporal evolution of the fungi caused by the vomit over the years under the conditions of relative isolation and high radiation that characterize this cave.
Despite evidence of damaging human impacts, cave paintings may again be threatened if visitors are allowed access.
In the last decade, considerable attention has been paid to the deterioration of the ...caves that house the world's most prominent Paleolithic rock art. This is exemplified by the caves of Lascaux (Dordogne, France) (
1
) and Altamira (Cantabria, Spain), both declared World Heritage Sites. The Altamira Cave has been closed to visitors since 2002. Since 2010, reopening the Altamira Cave has been under consideration. We argue that research indicates the need to preserve the cave by keeping it closed in the near future.
The paintings from Tomba della Scimmia, in Tuscany, are representative of the heavy bacterial colonization experienced in most Etruscan necropolises. The tomb remained open until the late 70's when ...it was closed because of severe deterioration of the walls, ceiling and paintings after decades of visits. The deterioration is the result of environmental changes and impacts suffered since its discovery in 1846. We show scanning electron microscopy and molecular studies that reveal the extent and nature of the biodeterioration. Actinobacteria, mainly Nocardia and Pseudonocardia colonize and grow on the tomb walls and this process is linked to the availability of organic matter, phyllosilicates (e.g. clay minerals) and iron oxides. Nocardia is found metabolically active in the paintings. The data confirm the specialization of the genera Nocardia and Pseudonocardia in the colonization of subterranean niches.
Abstract
The walls and ceiling of Altamira Cave, northern Spain, are coated with different coloured spots (yellow, white and grey). Electron microscopy revealed that the grey spots are composed of ...bacteria and bioinduced CaCO 3 crystals. The morphology of the spots revealed a dense network of microorganisms organized in well-defined radial and dendritic divergent branches from the central area towards the exterior of the spot, which is coated with overlying spheroidal elements of CaCO 3 and CaCO 3 nest-like aggregates. Molecular analysis indicated that the grey spots were mainly formed by an unrecognized species of the genus Actinobacteria. CO 2 efflux measurements in rocks heavily covered by grey spots confirmed that bacteria-forming spots promoted uptake of the gas, which is abundant in the cave. The bacteria can use the captured CO 2 to dissolve the rock and subsequently generate crystals of CaCO 3 in periods of lower humidity and/or CO 2. A tentative model for the formation of these grey spots, supported by scanning electron microscopy and transmission electron microscopy data, is proposed.
Atmospheric methane is rapidly lost when it enters humid subterranean critical and vadose zones (e.g., air in soils and caves). Because methane is a source of carbon and energy, it can be consumed by ...methanotrophic methane-oxidizing bacteria. As an additional subterranean sink, it has been hypothesized that methane is oxidized by natural radioactivity-induced radiolysis that produces energetic ions and radicals, which then trigger abiotic oxidation and consumption of methane within a few hours. Using controlled laboratory experiments, we tested whether radiolysis could rapidly oxidize methane in sealed air with different relative humidities while being exposed to elevated levels of radiation (more than 535 kBq m-3) from radon isotopes 222Rn and 220Rn (i.e., thoron). We found no evidence that radiolysis contributed to methane oxidation. In contrast, we observed the rapid loss of methane when moist soil was added to the same apparatus in the absence of elevated radon abundance. Together, our findings are consistent with the view that methane oxidizing bacteria are responsible for the widespread observations of methane depletion in subterranean environments. Further studies are needed on the ability of microbes to consume trace amounts of methane in poorly ventilated caves, even though the trophic and energetic benefits become marginal at very low partial pressures of methane.
The Etruscan civilisation originated in the Villanovan Iron Age in the ninth century BC and was absorbed by Rome in the first century BC. Etruscan tombs, many of which are subterranean, are one of ...the best representations of this culture. The principal importance of these tombs, however, lies in the wall paintings and in the tradition of rich burial, which was unique in the Mediterranean Basin, with the exception of Egypt. Relatively little information is available concerning the biodeterioration of Etruscan tombs, which is caused by a colonisation that covers the paintings with white, circular to irregular aggregates of bacteria or biofilms that tend to connect each other. Thus, these colonisations sometimes cover extensive surfaces. Here we show that the colonisation of paintings in Tomba del Colle is primarily due to bacteria of the order Rhizobiales (Alphaproteobacteria), which were likely influenced by the neighbouring rhizosphere community and the availability of nutrients from root exudates.
The presence of nestlings and other nest dwelling organisms in cavity nests alters the composition of gasses inside the cavity. Differential concentrations of gasses could be used by some parasites ...as a cue to localize their hosts. Here, we explored temporal variation in the concentration and isotopic signature of carbon dioxide (CO2) and methane (CH4) inside nest boxes of blue tits (Cyanistes caeruleus) during the nestling period (on days 3, 8, 13, 20, and 21 post-hatching) as well as several variables potentially affecting such variation. Finally, we checked whether differences in gas concentrations affect the abundance of different types of parasites affecting nestlings. Gas concentration and isotopic signature were significantly different between nest boxes and the forest during the nestling period. The CO2 concentration was higher inside nests than in the forest air, whereas CH4 concentration was lower. We expected to observe a positive correlation between the abundance of parasites actively seeking nests (i.e., blackflies, biting midges, and blowflies) and differences in gas concentration for those species that use these differences as a cue for host location. We observed that biting midge abundance was positively related to differences in CO2 between nest and forest air at day 20 of nestling age, indicating that this species can use these differences to locate hosts. We also found a positive relationship between blackfly abundance and differences in CH4 concentration. However, we hypothesize that the concentration of this gas inside nests may be related with bacterial activity; therefore, this relationship may be due to an effect of bacteria on blackflies and not to the effect of CH4 as an attraction cue for blackflies.
Purpose
We investigated the effects of human-induced disruption in a subterranean stable environment containing valuable Palaeolithic paintings and engravings (Ardales Cave, Southern Spain) using a ...double analytical approach.
Methods
An environmental monitoring system was installed in the cave to record temperature, relative humidity, carbon dioxide (CO
2
) and radon (
222
Rn) concentrations in air. In the same stations, an aerobiological sampling was conducted to quantify the level of airborne microorganisms.
Results
The combination of different methods allowed us to detect the extent of human-induced changes, confirming that these can be very hazardous in certain cave areas that should be apparently outside the scope of human disturbances, either by their remoteness to the visitor entrance or by being briefly visited.
Conclusions
The detection of evident anomalies in the environmental parameters and airborne microorganism concentration in the cave area housing the high density of paintings and engravings helps to control human disturbances and supports the direct application of this double approach for cave management purposes.
Understanding the dynamics and spatial distribution of gases in the subterranean atmospheres is essential to increase the reliability of carbon balances in karst ecosystems or the paleoclimate ...reconstructions based on cave deposits. This scientific information is also very valuable for cave managers to ensure the safety of visitors and the conservation of the subterranean heritage. Through a comprehensive monitoring of the main air parameters in a shallow temperate cave, we decipher the physical drivers and mechanisms involved in the CO2 and radon exchange between the cave and the outer atmosphere, and how this process is triggered by the changes of local weather. Our results reveal that the biphasic infiltration (water plus air) in the network of penetrative structures from the overlying soil and host rock exercise remarkable control over the cave environment, delaying the thermal response of the cave air to the outer climate-driven changes and also the gaseous transfer between the cave atmosphere and the exterior. The cave location concerning the karstified outcrop determines that this subterranean site acts as a gas emitter during summer, which is contrary to what happens in many other caves. Prominent gas entrapment at a micro-local level is also registered in some upper galleries.
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