Radon distribution and the ventilation of a limestone cave on Okinawa.

Tanahara, Akira; Taira, Hatsuo; Takemura, Morihisa

doi:10.2343/geochemj.31.49

Cited by 29 publications

(19 citation statements)

References 7 publications

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“…In general the ventilation of Postojna Cave is characterised by convective airflow, controlled mainly by the temperature difference between the cave and the outside atmosphere, as discussed by for one measurement location in the Velika Gora (Great Mountain) chamber of Postojna Cave. Different ventilation regimes in the cold and warm periods of the year are responsible for the observed seasonal pattern of radon concentration with low winter and high summer levels, as already reported for this Kobal et al, 1988;Vaupotič, 2008) and several other caves (Gillmore et al, 2002;Kowalczk and Froelich, 2010;Nagy et al, 2012;Perrier and Richon, 2010;Przylibski, 1999;Tanahara et al, 1997;Wilkening and Watkins, 1976).…”

Section: Introductionsupporting

confidence: 52%

“…The main sources of CO 2 in caves are diffusion from the epikarst, decomposition of organic matter and precipitation of calcite from supersaturated solutions. Many authors therefore include cave ventilation when modelling CO 2 variation over time in order to explain seasonality and trend (Baldini et al, 2008;Fernandez-Cortes et al, 2011;Milanolo and Gabrovšek, 2009;Tanahara et al, 1997). CO 2 was used in this study as an additional tool to characterise and explain the sources and reasons of high radon concentration and its variability in a dead-end passage in Postojna Cave.…”

Section: Introductionmentioning

confidence: 99%

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Reasons for large fluctuation of radon and CO<sub>2</sub> levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

Gregorič¹,

Vaupotič

Gabrovšek

2013

Nat. Hazards Earth Syst. Sci.

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Abstract. Measurements of radon concentration were performed at three geomorphologically different locations in Postojna Cave, Slovenia. In the part of the cave open to visitors, annual average radon activity concentrations of 3255 ± 1190 Bq m−3 and 2315 ± 1019 Bq m−3 were found at the lowest point (LP) and in the Lepe jame (Beautiful Caves, BC), respectively. A much higher average of 25 020 ± 12 653 Bq m−3 was characteristic of the dead-end passage Pisani rov (Gaily Coloured Corridor, GC), in which CO2 concentration also reached very high values of 4689 ± 294 ppm in summer. Seasonal variations of radon and CO2 levels in the cave are governed by convective airflow, controlled mainly by the temperature difference between the cave and the outside atmosphere. The following additional sources of radon and CO2 were considered: (i) flux of geogas from the Earth's crust through fractured rocks (radon and CO2 source), (ii) clay sediments inside the passage (radon source) and (iii) the soil layer above the cave (radon and CO2 source).

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Section: Introductionsupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Reasons for large fluctuation of radon and CO<sub>2</sub> levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

Gregorič¹,

Vaupotič

Gabrovšek

2013

Nat. Hazards Earth Syst. Sci.

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“…Some caves in US, Spain, and Japan were reported to experience fastest ventilation in winter (Wilkening & Watkins, 1976, Fernández et al, 1986, Tanahara et al, 1997, Buecher, 1999, Dueñas et al, 1999, and Banner et al, 2007. As…”

Section: U-shape Model In the Multiple-entrance Cavesmentioning

confidence: 99%

First assessment on the air CO2 dynamic in the show caves of tropical karst, Vietnam

Trinh¹,

Trinh²,

Fernández-Cortés³

et al. 2018

IJS

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Abstract:In this study, air, water, and host rock in show caves in a Vietnam's karst region was monitored and analyzed to identify the ventilation regime and track the cave air CO 2 sources. In general, the studied caves are well ventilated. In dynamic -multiple entrance caves, air ventilation is described with the use of U shape model. In static -single entrance cave, air circulation is explained by cold air trap model. Both ventilation models suggest that air is more circulated in winter than in summer. Seasonally, the cave air CO 2 increases from early spring to summer. Value in the deepest part of the single-entrance cave is approximately 1,000 ppmv and 8,000 ppmv in early spring and summer, respectively. In multiple-entrance and wet caves, CO 2 level is fairly constant all over the show section, increasing from 500 ppmv in early spring to 2,000 ppmv in summer. Data of microclimate, CO 2 content, and particularly δ 13 C show that cave air, particularly in single entrance cave, has higher CO 2 concentration during summer due to a stagnation of cave air circulation and an elevated CO 2 input from soil and epikarst. The cave air CO 2 increase is also observed after intense rainfalls. A factor that increase cave air CO 2 in show caves during the festive days could probably be huma n exhaling but the extent of human factor in these studied cave systems should be further investigated. Cave waters including cave pools and streams mediate CO 2 level in wet caves. Above all, the atmospheric fraction of CO 2 is always dominant (>60%) in all cave sections.Phong Nha -Ke Bang, microclimate, cave air ventilation, soil air CO 2 , human exhaling

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“…On the other hand, 210Pb produced from 222Rn decay in the ground water is presumably adsorbed on the inner surface because 222Rn con tent in the ground water is high (Tanahara et al, 1997;Asato et al, 1994).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Lively and Ney (1987) also showed that 210Pb resulting from 222Rn decay was found on surface of a cave rock and basement window glass with high concentrations. A great quantity of 222Rn in cave air is prob ably supplied by emanation from ground water at the same time of degassing of CO2 from the wa ter dripping into caves (Tanahara et al, 1997;Quinn, 1988;Lively and Ney, 1987). The excess 210Pb found on straw surfaces may be produced from its gaseous precursor 222Rn that exists with high concentrations in cave air.…”

Section: Introductionmentioning

confidence: 99%

Application of excess 210Pb dating method to stalactites.

et al. 1998

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Radon distribution and the ventilation of a limestone cave on Okinawa.

Cited by 29 publications

References 7 publications

Reasons for large fluctuation of radon and CO<sub>2</sub> levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

Reasons for large fluctuation of radon and CO<sub>2</sub> levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

First assessment on the air CO2 dynamic in the show caves of tropical karst, Vietnam

Application of excess 210Pb dating method to stalactites.

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Radon distribution and the ventilation of a limestone cave on Okinawa.

Cited by 29 publications

References 7 publications

Reasons for large fluctuation of radon and CO&lt;sub&gt;2&lt;/sub&gt; levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

Reasons for large fluctuation of radon and CO&lt;sub&gt;2&lt;/sub&gt; levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

First assessment on the air CO2 dynamic in the show caves of tropical karst, Vietnam

Application of excess 210Pb dating method to stalactites.

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Reasons for large fluctuation of radon and CO<sub>2</sub> levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)

Reasons for large fluctuation of radon and CO<sub>2</sub> levels in a dead-end passage of a karst cave (Postojna Cave, Slovenia)