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Speleology in Kazakhstan

Shakalov on 04 Jul, 2018
Hello everyone!   I pleased to invite you to the official site of Central Asian Karstic-Speleological commission ("Kaspeko")   There, we regularly publish reports about our expeditions, articles and reports on speleotopics, lecture course for instructors, photos etc. ...

New publications on hypogene speleogenesis

Klimchouk on 26 Mar, 2012
Dear Colleagues, This is to draw your attention to several recent publications added to KarstBase, relevant to hypogenic karst/speleogenesis: Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications Galdenzi,

The deepest terrestrial animal

Klimchouk on 23 Feb, 2012
A recent publication of Spanish researchers describes the biology of Krubera Cave, including the deepest terrestrial animal ever found: Jordana, Rafael; Baquero, Enrique; Reboleira, Sofía and Sendra, Alberto. ...

Caves - landscapes without light

akop on 05 Feb, 2012
Exhibition dedicated to caves is taking place in the Vienna Natural History Museum   The exhibition at the Natural History Museum presents the surprising variety of caves and cave formations such as stalactites and various crystals. ...

Did you know?

That beudantite is a cave mineral - pbfe3(aso4)(so4)(oh)6 [11].?

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Featured articles from Cave & Karst Science Journals
Chemistry and Karst, White, William B.
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Featured articles from other Geoscience Journals
Karst environment, Culver D.C.
Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs, Bontognali, Tomaso R.R.; D’Angeli Ilenia M.; Tisato, Nicola; Vasconcelos, Crisogono; Bernasconi, Stefano M.; Gonzales, Esteban R. G.; De Waele, Jo
Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
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Your search for saturated zone (Keyword) returned 86 results for the whole karstbase:
Showing 61 to 75 of 86
Tracer tests in karst hydrogeology and speleology, 2008, Goldscheider N. , Meiman J. , Pronk M. , Smart C.

This article presents an introduction to the fundamentals of tracing techniques and their application in cave and karst environments, illustrated by case studies from the Mammoth Cave, USA, and a small experimental site in Switzerland. The properties and limitations of the most important artificial tracers are discussed, and the available methods of tracer injection, sampling, online monitoring and laboratory analysis are presented. Fully quantitative tracer experiments result in continuous or discrete concentration-time data series, i.e. breakthrough curves, and concomitant discharge data, which make it possible to obtain detailed information about groundwater flow and contaminant transport. Within the frame of speleological investigations, tracer tests can help to resolve the active and often inaccessible part of cave and conduit networks and to obtain indications about the geometry and volume of the conduits. For hydrogeological studies, caves can in turn be used as natural experimental and monitoring sites inside the unsaturated or saturated zone of karst aquifer systems.


Hydrogeochemical processes as environmental indicators in drip water: Study of the Cueva del Agua (Southern Spain), 2008, Fernandezcortes A. , Calaforra J. M. , Snchezmartos F.

Karst caves exhibit a wide range of hydrological and hydrochemical responses to infiltration events, due to their physical heterogeneity space and dynamic variability over time, and due to non-Gaussian inputs (rain) and outputs (discharge). This paper reviews different approaches of studying seepage water in caves, in order to understand the infiltration regimen in the non-saturated zone of karst areas. As an illustration, we describe a four-year study of the active carbonate-water system the Cueva del Agua (Granada, southern Spain) that automatically logs the discharge from a stalactite. The results indicate that: (1) the drip water regime is not seasonal, but is linked instead to slow infiltration. Sudden changes in drip water regime occur due to infiltration along preferential flow paths and the draining of water of supersaturated water from reserves in the microfissure and pore system; (2) the drip rate is not linear over time. When dripping is constant, barometric oscillation of the air is the principal factor causing a chaotic a drip flow regime. Over a short period of two to three days, a mean variation in air pressure inside the cave of 10 (±3.7) mbar causes a oscillation the drip rate of 0.5 (±0.2) mm/h. The increase air translates into an the relative thickness of the gaseous phase of the drip water at the cost of the aqueous phase, so leading to a reduction the drip rate from the stalactite.


Some applications of geochemical and isotopic techniques to hydrogeology of the caves after research in two sites (Nerja Cave-S Spain, and Fourbanne system-French Jura), 2008, Mudry J. , Andreo B. , Charmoille A. , Lin C. , Carrasco F.

Caves constitute privileged sampling spots to investigate the hydrochemical behaviour of infiltration, but the representative nature of samples can limit their reach. Taking this into account many results can be obtained from chemistry of water sampled in the caves. Carbonate tracers enable to reconstruct the ‘history’ of drip water water, including rainfall and temperatures. Moreover, permanent drip waters prove durability of water stored in the unsaturated zone over the cave, and lags between rain inputs and drip output enable to evaluate transit time through the unsaturated zone. The comparison of input/output concentrations can also contribute to estimate the local water balance of the site.Finally, providing an access to the water table of the saturated zone, caves allow a calculation of mixing rates of infiltration water with water stored in the saturated zone.


Palaeoclimate Research in Villars Cave (Dordogne, SW-France), 2008, Genty, D.

Villars Cave is a typical shallow cave from South-West France (45.44°N; 0.78°E; 175 m asl) that has provided several speleothem palaeoclimatic records such as the millennial scale variability of the Last Glacial period and the Last Deglaciation. Monitoring the Villars cave environment over a 13-year period has helped in the understanding of the stable isotopic speleothem content and in the hydrology. For example, it was demonstrated that most of the calcite CaCO3 carbon comes from the soil CO2, which explains the sensitivity of the δ13C to any vegetation and climatic changes. Drip rate monitoring, carried out under four stalactites from the lower and upper galleries, has shown a well marked seasonality of the seepage water with high flow rates during winter and spring. A time delay of about two months is observed between the water excess (estimated from outside meteorological stations) and the drip rate in the cave. A great heterogeneity in the flow rate amplitude variations and in the annual quantity of water between two nearby stalactites is observed, confirming the complexity of the micro-fissure network system in the unsaturated zone. At a daily scale, the air pressure and drip rates are anti-correlated probably because of pressure stress on the fissure network. Cave air CO2 concentration follows soil CO2 production and is correlated with its δ13C content. Since the beginning of the monitoring, the cave air temperature, in both lower and upper galleries, displays a warming trend of ~+0.4°C±0.1/10yrs. This might be the consequence of the outside temperature increase that reaches the Villars Cave galleries through thermal wave conduction. Chemistry monitoring over a few years has shown that the seepage water of the lower gallery stations is significantly more concentrated in trace and minor elements (i.e. Sr, Mg, Ba, U) than the upper stations, probably due to the 10-20 m depth difference between these galleries, which implies a different seepage pathway and different water/rock interaction durations. There is also, in the elemental concentration (i.e. [Ca]), a seasonal signal which causes variation in the speleothem growth rates. Modern calcite deposit experiments conducted for several years have permitted the calculation of vertical growth rates, which are extremely high in Villars (i.e. 1.0 to 1.75 mm/yr). Pollen filter experiments in the cave have demonstrated that most of the pollen grain found in the cave comes from the air and not from the water. The specificity of the Villars Cave records is that the climatic variations were well recorded in the calcite δ13C whereas the δ18O is usually used in such studies. Overall, these results are helpful for the interpretation of speleothem records for palaeoclimatic reconstructions, but more work is needed, especially numerical modelling of the temperature, chemistry and hydrology.


Chemical and isotopic (d18O%, d2H%, d13C%, 222Rn%) multi-tracing for groundwater conceptual model of carbonate aquifer (Gran Sasso INFN underground laboratory central Italy), 2008, Adinolfi Falcone R. , Falgiani A. , Parisse B. , Petitta M. , Spizzico M. , Tallini M.

A hydrochemical and isotope study was conducted on the drainage waters of an underground laboratory, located inside the Gran Sasso massif (central Italy). The study was expected to improve the conceptual model of groundwater circulation at the base of an over 1000-thick unsaturated zone in the Gran Sasso partitioned karst aquifer. This lithostratigraphically and tectonically complex aquifer is typical of Africa–Europe thrust-andfold collision belt in the Mediterranean area. In this case, investigations on water–rock interactions during recharge in complex aquifers, overlaid by a thick unsaturated zone, have been made thanks to the strategic location of the Gran Sasso underground laboratories, located in the core of a huge carbonate aquifer. Knowledge of the local basic hydrogeological setting was the starting point for a detailed hydrogeochemical and isotopic study, which was carried out at the aquifer scale and at the fine scale in the underground laboratories. The water–rock interaction processes were investigated both spatially and in temporal sequences, analysing recharge waters and groundwater in the underground laboratories by multitracing techniques, including major ions and d18O&, d2H& and d13C& stable isotopes. Use of 222Rn provides information on transit time in the aquifer. Processes proved to be typical of carbonate rocks, with clear influence of vertical movement of water on chemical–physical parameters through the unsaturated zone. Conversely, in the saturated zone, these processes proved to be dominantly affected by local geological–structural conditions. A conceptual model with dual flow velocity is proposed, directly related to the local geological-structural setting. 222Rn decay enables to calculate an effective velocity of around 10 m/day for the fracture network, through the sequence of less permeable dolomites and underlying limestone. Lag time between recharge and chemical changes in the saturated zone testifies to an effective velocity of about 35 m/day for fast flow through recent and active extensional faults


Percolation and Particle Transport in the Unsaturated Zone of a Karst Aquifer, 2009, Pronk M. , Goldscheider N. , Zopfi J. , Zwahlen F.

Recharge and contamination of karst aquifers often occur via the unsaturated zone, but the functioning of this zone has not yet been fully understood. Therefore, irrigation and tracer experiments, along with monitoring of rainfall events, were used to examine water percolation and the transport of solutes, particles, and fecal bacteria between the land surface and a water outlet into a shallow cave. Monitored parameters included discharge, electrical conductivity, temperature, organic carbon, turbidity, particle-size distribution (PSD), fecal indicator bacteria, chloride, bromide, and uranine. Percolation following rainfall or irrigation can be subdivided into a lag phase (no response at the outlet), a piston-flow phase (release of epikarst storage water by pressure transfer), and a mixed-flow phase (increasing contribution of freshly infiltrated water), starting between 20 min and a few hours after the start of recharge event. Concerning particle and bacteria transport, results demonstrate that (1) a first turbidity signal occurs during increasing discharge due to remobilization of particles from fractures (pulse-through turbidity); (2) a second turbidity signal is caused by direct particle transfer from the soil (flow-through turbidity), often accompanied by high levels of fecal indicator bacteria, up to 17,000 Escherichia coli/100 mL; and (3) PSD allows differentiation between the two types of turbidity. A relative increase of fine particles (0.9 to 1.5 lm) coincides with microbial contamination. These findings help quantify water storage and percolation in the epikarst and better understand contaminant transport and attenuation. The use of PSD as ‘‘early-warning parameter’’ for microbial contamination in karst water is confirmed.


Mixing and transport of water in a karst catchment: a case study from precipitation via seepage to the spring, 2009, Schwarz K. , Barth J. A. C. , Postigorebollo C. , Grathwohl P.

One of the best-known and largest karst areas in Germany, the Blautopf Catchment, offers unique access to waters of the unsaturated zone through a large cave system. It was investigated with stable isotopes (18O/16O and D/H ratios expressed in permille = ‰) in precipitation, seepageand groundwater as tracers for water flow, mixing, and storage. The precipitation showed a distinct seasonality with _18O values between −2.9 and −24.6‰ during summer and winter, respectively. However, the isotope signals in seepage water in the caves as well as the discharge were almost completely buffered and ranged around an average _18O value of −10‰. This value was also close to the long-term average value of local precipitation, −9.3‰. The homogeneous isotopic composition of the Blautopf Spring was unexpected, as its highly variable discharge (0.3 to 32m3 s−1) is typical for a fast responsive karst system. These isotopic similarities could be explained by nearly complete mixing of the water already in the vadose zone. The data set therefore presents a case study to narrow down zones of mixing in karst catchments. It also confirms the minor role of the fast conduit system in the water balance of the Blautopf Catchment.

 


HYDROGEOLOGICAL FUNCTIONING OF A KARST AQUIFER DEDUCED FROM HYDROCHEMICAL COMPONENTS AND NATURAL ORGANIC TRACERS PRESENT IN SPRING WATERS. THE CASE OF YEDRA SPRING (SOUTHERN SPAIN), 2010, Mudarra M. , Andreo B.
The major chemical parameters, TOC and natural fluorescence of yedra spring, Malaga province, southern Spain were monitored from April 2008 to March 2009. The electrical conductivity and the concentrations of most major ions decreased following recharge periods. The TOC and NO3, representing tracers from the soil that infiltrate through the unsaturated zone, were found to vary inversely with the Mg2+ content, which is a natural indicator of groundwater residence time. Furthermore, a strong, direct relation was found between TOC and the natural fluorescence associated with humic and fulvic acids. Both parameters respond similarly to rainfall events, exhibiting significant increases during recharge followed by reductions during recession. This relation means that TOC mainly originates from organic acids. The results document rapid infiltration processes with a lag of less than one day following rainfall, which is typical of a karst aquifer with conduit flow, rapid drainage and limited natural regulation. The combined use of conventional hydrochemical parameters and natural organic tracers facilitates aquifer characterization and validates the vulnerability to contamination.

Evidence for a hypogene paleohydrogeological event at the prospective nuclear waste disposal site Yucca Mountain, Nevada, USA, revealed by the isotope composition of !uid-inclusion water, 2010, Dublyansky Yuri V. , Spö, Tl Christoph

Secondary calcite residing in open cavities in the unsaturated zone of Yucca Mountain has long been interpreted as the result of downward infiltration of meteoric water through open fractures. In order to obtain information on the isotopic composition (delta 18O) of the mineral-forming water we studied fluid inclusions from this calcite. Water was extracted from inclusions by heated crushing and the delta D values were measured using a continuous-low isotope-ratio mass spectrometry method. The delta 18O values were calculated from the delta 18O values of the host calcite assuming isotopic equilibrium at the temperature of formation determined by fuid-inclusion microthermometry. The delta D values measured in all samples range between −110 and −90‰, similar to Holocene meteoric water. Coupled delta 18O– delta D values plot significantly, 2 to 8‰, to the right of the meteoric water line. Among the various processes operating at the topographic surface and/or in the unsaturated zone only two processes, evaporation and water–rock exchange, could alter the isotope composition of percolatingwater. Our analysis indicates, however, that none of these processes could produce the observed large positive delta 18O-shifts. The latter require isotopic interaction between mineral-forming fluid and host rock at elevated temperature (N100 °C), which is only possible in the deepseated
hydrothermal environment. The stable isotope data are difficult to reconcile with a meteoric origin of the water from which the secondary minerals at Yucca Mountain precipitated; instead they point to the deep-seated provenance of the mineral-forming waters and their introduction into the unsaturated zone from below, i.e. a hypogene origin.


Relative importance of the saturated and the unsaturated zones in the hydrogeological functioning of karst aquifers: The case of Alta Cadena (Southern Spain), 2011, Mudarra M. , Andreo B.

From analysis of the hydrodynamic and hydrochemical responses of karst springs, it is possible to know the behaviour of the aquifers they drain. This manuscript aims to contribute to the characterization of infiltration process, and to determine the relative importance of the saturated zone and of the unsaturated zone in the hydrogeological functioning of carbonate aquifers, using natural hydrochemical tracers. Thus, chemical components together with temperature and electrical conductivity (both punctual and continuous records) have been monitored in three springs which drain Alta Cadena carbonate aquifer, Southern Spain. An evaluation of the percentage of the electrical conductivity frequency peaks determined for each of the three springs is linked to the chemical parameters that comprise the conductivity signal. One of these springs responds rapidly to precipitation (conduit flow system), due to the existence of a high degree of karstification in the unsaturated zone and in the saturated zone, both of which play a similar role in the functioning of the spring. Another spring responds to precipitation with small increases in water flow, somewhat lagged, because the aquifer has a low degree of karstification, even in the unsaturated zone, which seems to influence its functioning more strongly than does the saturated zone. The third spring drains a sector of the aquifer with a moderately developed degree of karstification, one that is intermediate between the other two, in which both the unsaturated zone and the saturated zone participate in the functioning of the spring, but with the latter zone having a stronger influence. These three springs show different hydrogeological functioning although they are in similar geological and climatic contexts, which show the heterogeneity of karst media and the importance of an adequate investigation for groundwater management and protection in karst areas.

Research highlights
- From analysis of the hydrodynamic and hydrochemical responses of karst springs. - Characterization of the relative importance of the saturated (SZ) and unsaturated (NSZ) zones - Villanueva del Rosario: NSZ and SZ play similar roles in the functioning of the system. ► Pita: NSZ seems to affect its functioning more than SZ. - Parroso: NSZ and SZ participate in the functioning of the system, but SZ is more active.


Radon and CO2 as natural tracers to investigate the recharge dynamics of karst aquifers, 2011, Savoy Ludovic, Surbeck Heinz, Hunkeler Daniel

This study investigated the use of radon (222Rn), a radioactive isotope with a half-life of 3.8 days, and CO2 as natural tracers to evaluate the recharge dynamics of karst aquifer under varying hydrological conditions. Dissolved 222Rn and carbon dioxide (CO2) were measured continuously in an underground stream of the Milandre test site, Switzerland. Estimated soil water 222Rn activities were higher than baseflow 222Rn activities, indicating elevated 222Rn production in the soil zone compared to limestone, consistent with a 226Ra enrichment in the soil zone compared to limestone. During small flood events, 222Rn activities did not vary while an immediate increase of the CO2 concentration was observed. During medium and large flood events, an immediate CO2 increase and a delayed 222Rn activity increase to up to 4.9 Bq/L and 11 Bq/L, respectively occurred. The detection of elevated 222Rn activities during medium and large flood events indicate that soil water participates to the flood event. A soil origin of the 222Rn is consistent with its delayed increase compared to discharge reflecting the travel time of 222Rn from the soil to the saturated zone of the system via the epikarst. A three-component mixing model suggested that soil water may contribute 4–6% of the discharge during medium flood events and 25–43% during large flood events. For small flood events, the water must have resided at least 25 days below the soil zone to explain the background 222Rn activities, taking into account the half-life of 222Rn (3.8 days). In contrast to 222Rn, the CO2 increase occurred simultaneously with the discharge increase. This observation as well as the CO2 increase during small flood events, suggests that the elevated CO2 level is not due to the arrival of soil water as for 222Rn. A possible explanation for the CO2 trend is that baseflow water in the stream has lower CO2 levels due to gas loss compared to water stored in low permeability zones. During flood event, the stored water is more rapidly mobilised than during baseflow with less time for gas loss. The study demonstrates that 222Rn and CO2 provides value information on the dynamics of groundwater recharge of karst aquifer, which can be of high interest when evaluating the vulnerability of such systems to contamination.


PaPRIKa: a method for estimating karst resource and source vulnerabilityapplication to the Ouysse karst system (southwest France) , 2011, Kavouri Konstantina, Plagnes Valerie, Tremoulet Joel, Dorfliger Nathalie, Rejiba Faycal, Marchet Pierre

The intrinsic vulnerability mapping method, PaPRIKa, is proposed as a common basis for karst groundwater protection in France. PaPRIKa is a specialized method for studying karst aquifers, derived from updating the RISKE and EPIK methods. Both the structure and functioning of karst aquifers are considered in order to develop a resource and source-vulnerability mapping method. PaPRIKa means Protection of aquifers from the assessment of four criteria: P for protection (considering the most protective aspects among parameters related to soil cover, unsaturated zone and epikarst behavior), R for rock type, I for infiltration and Ka for karstification degree. The Ouysse karst system, located in the Causses area in southwest France, is one of the nine pilot sites where this method was tested and standardized. The specificities of the Ouysse system such as the size of the catchment area, the spatial variability of the karst network development, the thick infiltration zone and the system’s dual character (both karst and non-karst areas), have provided a valuable field of application. The vulnerability of the resource was assessed for the entire catchment area, while source-orientated cartography was attempted for the catchment areas of the three different capture works used for drinking water.


Radon and CO2 as natural tracers to investigate the recharge dynamics of karst aquifers, 2011, Savoy Ludovic, Surbeck Heinz, Hunkeler Daniel

This study investigated the use of radon (222Rn), a radioactive isotope with a half-life of 3.8 days, and CO2 as natural tracers to evaluate the recharge dynamics of karst aquifer under varying hydrological conditions. Dissolved 222Rn and carbon dioxide (CO2) were measured continuously in an underground stream of the Milandre test site, Switzerland. Estimated soil water 222Rn activities were higher than baseflow 222Rn activities, indicating elevated 222Rn production in the soil zone compared to limestone, consistent with a 226Ra enrichment in the soil zone compared to limestone. During small flood events, 222Rn activities did not vary while an immediate increase of the CO2 concentration was observed. During medium and large flood events, an immediate CO2 increase and a delayed 222Rn activity increase to up to 4.9 Bq/L and 11 Bq/L, respectively occurred. The detection of elevated 222Rn activities during medium and large flood events indicate that soil water participates to the flood event. A soil origin of the 222Rn is consistent with its delayed increase compared to discharge reflecting the travel time of 222Rn from the soil to the saturated zone of the system via the epikarst. A three-component mixing model suggested that soil water may contribute 4–6% of the discharge during medium flood events and 25–43% during large flood events. For small flood events, the water must have resided at least 25 days below the soil zone to explain the background 222Rn activities, taking into account the half-life of 222Rn (3.8 days). In contrast to 222Rn, the CO2 increase occurred simultaneously with the discharge increase. This observation as well as the CO2 increase during small flood events, suggests that the elevated CO2 level is not due to the arrival of soil water as for 222Rn. A possible explanation for the CO2 trend is that baseflow water in the stream has lower CO2 levels due to gas loss compared to water stored in low permeability zones. During flood event, the stored water is more rapidly mobilised than during baseflow with less time for gas loss. The study demonstrates that 222Rn and CO2 provides value information on the dynamics of groundwater recharge of karst aquifer, which can be of high interest when evaluating the vulnerability of such systems to contamination.


Radon and CO2 as natural tracers to investigate the recharge dynamics of karst aquifers, 2011, Savoy Ludovic, Surbeck Heinz, Hunkeler Daniel

This study investigated the use of radon (222Rn), a radioactive isotope with a half-life of 3.8 days, and CO2 as natural tracers to evaluate the recharge dynamics of karst aquifer under varying hydrological conditions. Dissolved 222Rn and carbon dioxide (CO2) were measured continuously in an underground stream of the Milandre test site, Switzerland. Estimated soil water 222Rn activities were higher than baseflow 222Rn activities, indicating elevated 222Rn production in the soil zone compared to limestone, consistent with a 226Ra enrichment in the soil zone compared to limestone. During small flood events, 222Rn activities did not vary while an immediate increase of the CO2 concentration was observed. During medium and large flood events, an immediate CO2 increase and a delayed 222Rn activity increase to up to 4.9 Bq/L and 11 Bq/L, respectively occurred. The detection of elevated 222Rn activities during medium and large flood events indicate that soil water participates to the flood event. A soil origin of the 222Rn is consistent with its delayed increase compared to discharge reflecting the travel time of 222Rn from the soil to the saturated zone of the system via the epikarst. A three-component mixing model suggested that soil water may contribute 4–6% of the discharge during medium flood events and 25–43% during large flood events. For small flood events, the water must have resided at least 25 days below the soil zone to explain the background 222Rn activities, taking into account the half-life of 222Rn (3.8 days). In contrast to 222Rn, the CO2 increase occurred simultaneously with the discharge increase. This observation as well as the CO2 increase during small flood events, suggests that the elevated CO2 level is not due to the arrival of soil water as for 222Rn. A possible explanation for the CO2 trend is that baseflow water in the stream has lower CO2 levels due to gas loss compared to water stored in low permeability zones. During flood event, the stored water is more rapidly mobilised than during baseflow with less time for gas loss. The study demonstrates that 222Rn and CO2 provides value information on the dynamics of groundwater recharge of karst aquifer, which can be of high interest when evaluating the vulnerability of such systems to contamination.


Geochemical evolution of groundwater in the unsaturated zone of a karstic massif, using the PCO2SIc relationship, 2012, Peyraube N. , Lastennet R. , Denis A.

In karstic environments, groundwater is strongly influenced by CO2 partial pressure variations of air present in the infiltration zone of these aquifers. In order to characterize the geochemical changes in groundwater as it moves through the infiltration zone, we monitored various rising springs in the perched karstic aquifer of Cussac (Dordogne, France), and measured the CO2 partial pressure in air of a nearby cavity (the Cussac Cave) for 24 months. Our method is based on the relationship between the saturation index with respect to calcite (SIc) and the CO2 partial pressure at atmospheric equilibrium with water. We distinguished a value for this last parameter when water is at equilibrium with respect to calcite (SIc = 0) called saturation CO2 partial pressure. The use of this parameter can provide information on flow conditions and relationships between water, air, and rock. Cussac aquifer is a suitable area to apply these methods because of its small size, numerous springs, and a cave that provides data for CO2 partial pressure condition inside the massif. Results show that most of the calcium-carbonate mineralization is acquired in the epikarst followed by a precipitation phase in the upper part of the infiltration zone. Groundwater reaches the saturated zone with some degree of saturation depending on CO2 partial pressure variations in air inside the massif.


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