Partial pressures of CO2 in epikarstic zone deduced from hydrogeochemistry of permanent drips, the Moravian Karst, Czech Republic

Faimon, Jiřı́; Ličbinská, Monika; Zajíček, Petr; Šráček, Ondra

doi:10.3986/ac.v41i1.47

Cited by 32 publications

(32 citation statements)

References 41 publications

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“…In both caves, pCO 2 increases in the summer months, with the highest concentration observed at the end of the growing season. Similar findings are reported in Banner et al (2007), Liñán et al (2008), Faimon et al (2012), Cowan et al (2013), Mandić et al (2013), and Lang et al (2016). The pCO 2 plateau noticed in Drac between August and early November is due to this cave's particular air circulation.…”

Section: Cave Air and Water Temperaturessupporting

confidence: 85%

Interactions between surface conditions, the Mediter-ranean Sea, and cave climate within two littoral caves in Mallorca: implications for the formation of phreatic overgrowths on speleothems

Boop¹,

Wynn²,

Thompson³

et al. 2017

JCKS

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Phreatic overgrowths on speleothems from Mallorca's littoral caves are valuable markers of former sea-level stands. These carbonate encrustations form as CO 2 degasses from brackish cave water that is hydrologically connected to the Mediterranean Sea. This study uses time series analysis to document relationships between surface conditions of temperature, barometric pressure, precipitation, tidal level of the Mediterranean Sea, and the coastal caves' microenvironment of temperature, partial pressure of CO 2 (pCO 2 ), and water level to contextualize overgrowth formation in Cova des Pas de Vallgornera (Vallgornera) and Coves del Drac (Drac). Water level in both caves was an attenuated semidiurnal function of Mediterranean Sea level with a lag of about four hours. The impact of individual rainfall events on cave water level was negligible during the study period. pCO 2 of cave air at both sites reached an annual maximum in September and decreased rapidly when surface air temperature fell below the cave air temperature (mean~19 8C). As this threshold was reached, cooler and denser tropospheric air descended into the caves, initiating cave ventilation and displacing high-pCO 2 cave air that had accumulated. Observed pCO 2 was lower in Drac than in Vallgornera, and had small daily fluctuations because of bigger passages, fewer constrictions, and a large collapse entrance. The frequency and magnitude of pCO 2 fluctuations were higher in Vallgornera than in Drac, with both caves showing twicedaily water level maxima causing displacement of high-pCO 2 air from the cave alternating with water level minima causing tropospheric air to enter the cave via a ''piston effect.'' A secondary control on pCO 2 variation can be attributed to variation in tropospheric barometric pressure. Thus, the geochemical conditions favorable for overgrowth formation are, in part, the result of this tidally-controlled cycle of cave-water level. The cycle causes cavetroposphere air exchange that drives CO 2 degassing, and therefore, the formation of phreatic overgrowths on speleothems.

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Section: Cave Air and Water Temperaturessupporting

confidence: 85%

Interactions between surface conditions, the Mediter-ranean Sea, and cave climate within two littoral caves in Mallorca: implications for the formation of phreatic overgrowths on speleothems

Boop¹,

Wynn²,

Thompson³

et al. 2017

JCKS

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“…Table II). Cave air pCO 2 higher than soil values has been documented in other mid latitude caves (Renault, 1968;Faimon et al, 2012b): in a study of Aven d'Orgnac, Bourges et al (2001) demonstrated that high cave air CO 2 concentrations (values up to 45 000 ppmv) are related to poor ventilation and CO 2 fluxes from the soil and epikarst entering into the cave through a microfissure network. This interpretation can also be applied for Bus del Diaol as supported by several dripwater analyses which exhibit a mean dissolved CO 2 concentration corresponding to 7290 ± 2475 ppmv with maximum values of 11800 ppmv Borsato et al, submitted for publication).…”

Section: Resultsmentioning

confidence: 90%

Carbon dioxide concentration in temperate climate caves and parent soils over an altitudinal gradient and its influence on speleothem growth and fabrics

Borsato

Frisia

Miorandi³

2015

Earth Surf Processes Landf

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Carbon dioxide (CO 2 ) concentrations in caves and parent soils in the Italian Alps have been studied along a 2100 m altitudinal range -corresponding to a mean annual temperature (MAT) range of 12°C -in order to investigate the relationship between MAT, soil pCO 2 and cave air pCO 2 , and to test the influence of soil pCO 2 on speleothem growth and fabric to ultimately gain insight into their palaeoclimatic significance in temperate climate settings.Our findings indicate that soil CO 2 is linearly correlated to MAT and its mean annual concentration is described by the equation: soil CO 2 (ppmv) = 1112 + 460 MAT. Soil pCO 2 can also be exponentially correlated to actual evapotranspiration. The pCO 2 in the aquifer is linearly correlated to MAT at the infiltration site and is more influenced by summer soil pCO 2 . Cave air CO 2 in the innermost part of the caves exhibits a similar seasonal pattern, and commonly reaches concentrations of about 15% to 35%, with respect to the corresponding soil values, and is exponentially correlated to the MAT at the infiltration site.The combination of these parameters (soil pCO 2 , dripwater pCO 2 and cave air pCO 2 ) results in speleothem growth and controls their fabrics which are typical of four MAT/elevation belts broadly corresponding to the present-day vegetation zones. In the lower montane zone [100-800 m above sea level (a.s.l.)] speleothems mostly consist of columnar fabric, in the upper montane zone (800-1600 m a.s.l.) both columnar and dendritic fabrics are common, the Subalpine zone (1600-2200 m a.s.l.) is characterized mostly by moonmilk deposits, whereas in the Alpine zone (above 2200 m a.s.l.) no speleothems are forming today. Therefore, fabric changes in fossil speleothem can potentially be used to reconstruct MAT changes in temperate climate karst areas.

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“…Spatial variability in pCO 2 could also be caused by spatial variability in concentrations of CO 2 gas in the vadose zone (Gulley et al 2014). While conceptual models of dissolution in karst hydrogeology textbooks generally consider CO 2 concentrations to be highest in the soil (Ford and Williams 2007), CO 2 concentrations are often higher in the vadose zone below the soil horizon (Wood and Petraitis 1984;Wood 1985;Baldini et al 2006;Benavente et al 2010;Faimon et al 2012;Peyraube et al 2012). The origin of this CO 2 gas is a combination of microbial oxidation of DOC that has been flushed into and accumulated within the vadose zone (Wood and Petraitis 1984) as well as root respiration (Wong and Banner 2010;Breecker et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Heterogeneous distributions of CO₂ may be more important for dissolution and karstification in coastal eogenetic limestone than mixing dissolution

Gulley

Martin

Moore

et al. 2015

Earth Surf Processes Landf

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Mixing dissolution, a process whereby mixtures of two waters with different chemical compositions drive undersaturation with respect to carbonate minerals, is commonly considered to form cavernous macroporosity (e.g. flank margin caves and banana holes) in eogenetic karst aquifers. On small islands, macroporosity commonly originates when focused dissolution forms globular chambers lacking entrances to the surface, suggesting that dissolution processes are decoupled from surface hydrology. Mixing dissolution has been thought to be the primary dissolution process because meteoric water would equilibrate rapidly with calcium carbonate as it infiltrates through matrix porosity and because pCO2 was assumed to be homogeneously distributed within the phreatic zone. Here, we report data from two abandoned well fields in an eogenetic karst aquifer on San Salvador Island, Bahamas, that demonstrate pCO2 in the phreatic zone is distributed heterogeneously. The pCO2 varied from less than log −2.0 to more than log −1.0 atm over distances of less than 30 m, generating dissolution in the subsurface where water flows from regions of low to high pCO2 and cementation where water flows from regions of high to low pCO2. Using simple geochemical models, we show dissolution caused by heterogeneously distributed pCO2 can dissolve 2.5 to 10 times more calcite than the maximum amount possible by mixing of freshwater and seawater. Dissolution resulting from spatial variability in pCO2 forms isolated, globular chambers lacking initial entrances to the surface, a morphology that is characteristic of flank margin caves and banana holes, both of which have entrances that form by erosion or collapse after cave formation. Our results indicate that heterogeneous pCO2, rather than mixing dissolution, may be the dominant mechanism for observed spatial distribution of dissolution, cementation and macroporosity generation in eogenetic karst aquifers and for landscape development in these settings. Copyright © 2015 John Wiley & Sons, Ltd.

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Partial pressures of CO2 in epikarstic zone deduced from hydrogeochemistry of permanent drips, the Moravian Karst, Czech Republic

Cited by 32 publications

References 41 publications

Interactions between surface conditions, the Mediter-ranean Sea, and cave climate within two littoral caves in Mallorca: implications for the formation of phreatic overgrowths on speleothems

Interactions between surface conditions, the Mediter-ranean Sea, and cave climate within two littoral caves in Mallorca: implications for the formation of phreatic overgrowths on speleothems

Carbon dioxide concentration in temperate climate caves and parent soils over an altitudinal gradient and its influence on speleothem growth and fabrics

Heterogeneous distributions of CO₂ may be more important for dissolution and karstification in coastal eogenetic limestone than mixing dissolution

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Partial pressures of CO2 in epikarstic zone deduced from hydrogeochemistry of permanent drips, the Moravian Karst, Czech Republic

Cited by 32 publications

References 41 publications

Interactions between surface conditions, the Mediter-ranean Sea, and cave climate within two littoral caves in Mallorca: implications for the formation of phreatic overgrowths on speleothems

Interactions between surface conditions, the Mediter-ranean Sea, and cave climate within two littoral caves in Mallorca: implications for the formation of phreatic overgrowths on speleothems

Carbon dioxide concentration in temperate climate caves and parent soils over an altitudinal gradient and its influence on speleothem growth and fabrics

Heterogeneous distributions of CO2 may be more important for dissolution and karstification in coastal eogenetic limestone than mixing dissolution

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Heterogeneous distributions of CO₂ may be more important for dissolution and karstification in coastal eogenetic limestone than mixing dissolution