Radon in caves

Cigna, Arrigo A.

doi:10.5038/1827-806x.34.1.1

Cited by 72 publications

(45 citation statements)

References 26 publications

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“…In addition to elevated radon levels, as found in many caves worldwide (Hakl et al, 1997;Cigna, 2005;Field, 2007;Vaupotič, 2010;Kávási et al, 2010), f un values are also high (Vaupotič, 2008b), as also in some other caves (Cheng et al, 1997;Sainz et al, 2007;Thinová & Burian, 2008). They are considerably higher than in Slovenian kindergartens (Vaupotič, 2007), schools (Vaupotič & Kobal, 2006) and wineries (Vaupotič, 2008a).…”

Section: Postojna Cavementioning

confidence: 92%

Nano Particles Including Radon Decay Products in Ambient Air

Vaupotič¹

2011

Chemistry, Emission Control, Radioactive Pollution and Indoor Air Quality

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Section: Postojna Cavementioning

confidence: 92%

Nano Particles Including Radon Decay Products in Ambient Air

Vaupotič¹

2011

Chemistry, Emission Control, Radioactive Pollution and Indoor Air Quality

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“…The highest concentrations are observed at night, when there is little or no ventilation 30,41 . In this regard, caves are suitable locations to storing underground air with high radon activity 42 , particularly, when the underground atmosphere has a low air renewal rate (for example, Castañar Cave 16,43 ). It is expected that there will be a high density of ions in such environments, and this is borne out by the measurements made in the subterranean sites that were studied.…”

Section: Articlementioning

confidence: 99%

Subterranean atmospheres may act as daily methane sinks

et al. 2015

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In recent years, methane (CH 4 ) has received increasing scientific attention because it is the most abundant non-CO 2 atmospheric greenhouse gas (GHG) and controls numerous chemical reactions in the troposphere and stratosphere. However, there is much that is unknown about CH 4 sources and sinks and their evolution over time. Here we show that near-surface cavities in the uppermost vadose zone are now actively removing atmospheric CH 4 . Through seasonal geochemical tracing of air in the atmosphere, soil and underground at diverse geographic and climatic locations in Spain, our results show that complete consumption of CH 4 is favoured in the subsurface atmosphere under near vapour-saturation conditions and without significant intervention of methanotrophic bacteria. Overall, our results indicate that subterranean atmospheres may be acting as sinks for atmospheric CH 4 on a daily scale. However, this terrestrial sink has not yet been considered in CH 4 budget balances. M ethane (CH 4 ) is currently the most abundant non-CO 2 greenhouse gas (GHG) in the atmosphere, reaching a global average concentration of B1,800 p.p.b. at midnorthern latitudes 1 . Despite significant research progress in recent years, large uncertainties remain about the CH 4 budget and its evolution over time because there is a lack of knowledge about CH 4 sinks and sources [2][3][4][5] . Superimposed on the long-term trend of increasing atmospheric CH 4 , there is significant interannual variability 1,6,7 , and the sources of variation remain controversial 8 .Current CH 4 estimates account for B22% of the total forcing potential of all long-lived GHGs 9 . By weight, CH 4 is 28 times more effective at trapping heat in the atmosphere than CO 2 over a 100-year period 10 . Sensible mitigation strategies also require a quantitative understanding of the CH 4 budget regarding emissions and sinks 11 . The total global emissions of CH 4 are constrained reasonably well by atmospheric observations and estimates of its lifetime, based on multiple atmospheric CH 4 inversion models (top-down studies). However, the uncertainties concerning emissions/consumption from individual sources/ sinks 12 are greater, and they are poorly constrained by the current atmospheric observation network 6 . Some unaccounted sinks (or sources) could contribute the global CH 4 budget and its long-term variations.The Earth's surface exerts its influence on the free atmosphere through the atmospheric boundary layer. This lowest portion of the atmosphere ranges from a few tens of metres to 1-2-km deep 13 . The subsurface atmosphere is usually overlooked as an important part of this boundary layer. At the top of the subsurface layer in the vadose zone (below the subsoil and above the groundwater table) highly specific biogeochemical processes occur, which may act as regulators of gas exchanges between the surface and the free atmosphere.The uppermost part of the vadose zone may contain large amounts of underground air, that is, a CO 2 -rich air reservoir permeating the unsaturated...

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“…Differences between the parameters could be due to the distinct recharge velocities. While radon exhalation is produced at a constant rate characteristic of each rock (Cigna, 2005), CO 2 inlet to the cave is linked to variations on the CO 2 concentration of the soil and the vadose zone, which may vary throughout the year. If ventilation does not exclusively control gases concentration inside Castañar de Ibor cave, differences between the gases recharge velocities could be related to different factors controlling gases production.…”

Section: Sources Of Variation In δ 13mentioning

confidence: 99%

Abiotic and seasonal control of soil-produced CO2 efflux in karstic ecosystems located in Oceanic and Mediterranean climates

Garcia-Anton

Cuezva

Fernández-Cortés

et al. 2017

Atmospheric Environment

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This study characterizes the processes involved in seasonal CO 2 exchange between soils and shallow underground systems and explores the contribution of the different biotic and abiotic sources as a function of changing weather conditions. We spatially and temporally investigated five karstic caves across the Iberian Peninsula, which presented different microclimatic, geologic and geomorphologic features. The locations present Mediterranean and Oceanic climates. Spot air sampling of CO 2 (g) and δ 13 CO 2 in the caves, soils and outside atmospheric air was periodically conducted. The isotopic ratio of the source contribution enhancing the CO 2 concentration was calculated using the Keeling model. We compared the isotopic ratio of the source in the soil (δ 13 C s -soil) with that in the soil-underground system (δ 13 C s -system).Although the studied field sites have different features, we found common seasonal trends in their values, which suggests a climatic control over the soil air CO 2 and the δ 13 CO 2 of the sources of CO 2 in the soil (δ 13 C s -soil) and the system (δ 13 C s -system). The roots respiration and soil organic matter degradation are the main source of CO 2 in underground environments, and the inlet of the gas is mainly driven by diffusion and advection. Drier and warmer conditions enhance soil-exterior CO 2 interchange, reducing the CO 2 concentration and increasing the δ 13 CO 2 of the soil air. Moreover, the isotopic ratio of the source of CO 2 in both the soil and the system tends to heavier values throughout the dry and warm season.We conclude that seasonal variations of soil CO 2 concentration and its 13 C/ 12 C isotopic ratio are mainly regulated by thermo-hygrometric conditions. In cold and wet seasons, the increase of soil moisture reduces soil diffusivity and allows the storage of CO 2 in the subsoil. During dry and warm seasons, the evaporation of soil water favours diffusive and advective transport of soil-derived CO 2 to the atmosphere. The soil CO 2 diffusion is enough important during this season to modify the isotopic ratio of soil produced CO 2 (3-6‰ heavier). Drought induces release of CO 2 with an isotopic ratio heavier than produced by organic sources. Consequently, climatic conditions drive abiotic processes that turn regulate a seasonal storage of soilproduced CO 2 within soil and underground systems. The results here obtained imply that abiotic emissions of soil-produced CO 2 must be an inherent consequence of droughts, which intensification has been forecasted at global scale in the next 100 years.

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Radon in caves

Cited by 72 publications

References 26 publications

Nano Particles Including Radon Decay Products in Ambient Air

Nano Particles Including Radon Decay Products in Ambient Air

Subterranean atmospheres may act as daily methane sinks

Abiotic and seasonal control of soil-produced CO2 efflux in karstic ecosystems located in Oceanic and Mediterranean climates

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