L'atmosphère de la grotte de Ramioul

in Bulletin de la Société Royale Belge d'Etudes Géologiques et Archéologiques "Les Chercheurs de Wallonie" (2010), hors-série n°3

Depuis 2004, un puits de 30 m de la grotte de Ramioul dégage du dioxyde de cargone à des concentrations atteignant 8%. Les concentrations de CO2, O2 et CO ont été enregistrées depuis 2008. Les ... [more ▼]

Depuis 2004, un puits de 30 m de la grotte de Ramioul dégage du dioxyde de cargone à des concentrations atteignant 8%. Les concentrations de CO2, O2 et CO ont été enregistrées depuis 2008. Les histogrammes de CO2 montrent des maximums hivernaux, des minimums en été, et une production 12 à 20 fois plus grande que les autres grottes de Belgique. Le CO2 provient probablement de l'oxydation de la pyrite par les eaux d'infiltration. [less ▲]

Extreme increase of CO2 in belgian caves

in ICS 2009 Proceedings (2009, July)

We began making CO2 measurements in Belgian caves in 1966. Analyses were conducted in cave halls, galleries, fissures and shafts, in various seasons and at different levels above the floors of the ... [more ▼]

We began making CO2 measurements in Belgian caves in 1966. Analyses were conducted in cave halls, galleries, fissures and shafts, in various seasons and at different levels above the floors of the conduits, and in the absence or presence of other human beings. Our first results were published in 1968. From that time on, we have carried out studies in Poland, Quebec, China and other countries but we have focused most of our work in Belgium. We have discovered over these forty years of study, a strong increase in the observed values of CO2 in Belgian caves. For example, a few of our observations follow. “Trou Joney” (Comblain-au-Pont, province of Liege) is a small and shallow cave. We measured at the central point of the main gallery, 1870 ppm CO2 in July 1966, and 13800 ppm at the same location in July 2007. At the bottom of the shaft of the “Comblain-au Pont” cave, we measured 600 ppm in July 1966 and found 1500 ppm in July 2008. In “La Merveilleuse” cave (Dinant, province of Namur), we measured 800 ppm at the central point of the Big Hall in August 1990, rising to 1700 ppm in August 2008. In the main gallery of the “Fontaine de Rivire” cave (Hamoir, province of Liege), we found 5000 ppm in August 1972, increasing to 9400 ppm in 2008. We conclude that the CO2 content of the atmospheres of many caves in Belgium at least, is very sharply getting higher. The increase is very variable, but omnipresent. Are our measurements significant? We believe that we have validated our instruments and our methods. The increase is probably not a result of local industrial activities. The CO2 curves of Mauna Loa Observatory (Hawaii) and “Mace Head” (Ireland) both show an increase of atmospheric carbon dioxide during the last half century. However, the upsurge of CO2 observed in the caves is much greater than the increase in those well-known surface measurements. There is a very complex interrelationship between temperature, vegetation and biomass activity, and CO2 in the soil and underground. The increase of any one of these three parameters can induce changes in the two others, and hence in the partial pressure of CO2 in cave air. [less ▲]

PROPOS DISPARATES AUTOUR DE LA GÉOGRAPHIE PHYSIQUE

in Bulletin de la Société géographique de Liège (2009), 52

Rambling thoughts about physical geography Theories and paradigms succeed each other as time passes by. Some of the paradigms display a strong tendency to degenerate into laws and rules. Applied research ... [more ▼]

Rambling thoughts about physical geography Theories and paradigms succeed each other as time passes by. Some of the paradigms display a strong tendency to degenerate into laws and rules. Applied research requires team work and hierarchy. It should not be the only kind of research. Financial support is essential to support fundamental research, some of which must remain independent. Systemic approach to research, even in physical geography, thrusts the Human to the forefront. Man becomes an agent, as well as a subject to the process. Research should be structured and open to provide us with the most essential elements necessary, to correctly validate the theories and to be useful to mankind. [less ▲]

Contribution à l'étude du climat de trois cavités souterraines belges

in Bulletin de la Société Royale Belge d'Etudes Géologiques et Archéologiques (2007), XLVI

Some temperature and CO2 measures have been made for one year in the cave of Ramioul and in the cave of Comblain-au-Pont, and for six months in the underground quarry of Petit-Lanaye inférieure ... [more ▼]

Some temperature and CO2 measures have been made for one year in the cave of Ramioul and in the cave of Comblain-au-Pont, and for six months in the underground quarry of Petit-Lanaye inférieure. Temperature has been measured by dataloggers. These measures and the comparison between the different caves contributed to a better understanding of their climates. In the cave of Ramioul, closed by non insulated doors, the air movements are relatively low but there are some heat exchanges between the outside and inside air by conduction through the doors. The cave can be divided into two parts each with a different climatic behaviour. High and dangerous CO2 rates have already been measured in this cave. Rates fluctuate in an irregular way and without any connection with the natural seasonal cycle, and the CO2 origins stay uncertain. The cave of Comblain-au-Pont can be divided into two major parts: one enclosed and the other ventilated. The ventilated region is a “wind tube” during the winter, but it doesn’t reverse in the summer. On a larger scale, this region can be considered as a cold air trap despite its two exits, since it has a descendant morphology. <br />In the underground carry of Petit-Lanaye inférieure, the low number of data doesn’t allow a complete diagnosis of the climate organisation, but can give a first idea for the summer period. We can already distinguish some parts that are more or less influenced by the outside temperature fluctuations, probably in relation with some air movements which organised <br />themselves in a complex way in the labyrinthic galleries network. [less ▲]

Karsts des craies et calcarénites de la Montagne Saint-Pierre (Basse Meuse liégeoise)

in Bulletin des Chercheurs de la Wallonie (2007), XLVI

The “Montagne Saint-Pierre” (Sint Pietersberg) is a separate part of the Hesbaye plateau, isolated between the lower valleys of the Geer and the Meuse rivers. It is exploited by a big open-air quarry and ... [more ▼]

The “Montagne Saint-Pierre” (Sint Pietersberg) is a separate part of the Hesbaye plateau, isolated between the lower valleys of the Geer and the Meuse rivers. It is exploited by a big open-air quarry and by numerous underground quarries developing galleries on hundreds of kilometers long. Excavated in Cretaceous chalk and calcarenite, these artificial networks allow an exceptional 3-D observation of karsts inside a very porous and permeable rock, less favourable to a concentrated solution. The most numerous of them are “organ pipes” or “earth pipes”. They are vertical tubular solution pipes that may exceed 60 m in depth. Sponge networks and subhorizontal caves occur, without any visible connection with fracturation. Finally, downwards to at least 20 m below the alluvial plain of the Meuse river, pluridecametric nodes of weathered chalk are found. By their size and rounded morphology, the nodes resemble to the natural caves occurring in the calcarenite and intersected by the underground quarries. All the studied karsts allow us to propose a scenario for the genesis of a polyphase karst system. Independently of surface conditions, caves are generated deeply in the phreatic zone (endokarsts). During the downcutting of theMeuse valley, and related to the fluvial terraces, solution pipes (input karsts) are generated. Due to the valley incision and to the lowering of the aquifer,theses solution pipes progress downward and cut the endokarsts. A concentrated water circulation takes place. In the dewatered upper part of the system, caves cut by solution pipes are rapidly filled by superficial deposits. The high porosity of the calcarenite makes it comparable to a sponge. The rock absorbs quickly the out-flows coming from the surface and causes a rapid deposit of the fine particles transported inside horizontal passages. The sealing of these conduits allows their conservation inside a very crumbly rock. [less ▲]

La Grotte et l'Abîme de Comblain-au-Pont

Book published by Découverte de Comblain-au-Pont et environs, ASBL (2007)

Summary: Historical review; Geology; Cave genesis; Climate; Fauna; Paleontology

Le monde souterrain : la genèse des cavernes

in Bulletin de la Société Royale des Sciences de Liège (2006), 75

Balade géologique le long de l'Ourthe, de Liège à Comblain-au-Pont

Article for general public (2004)

The regional governement of Wallonia (Région wallonne, DGARNE) is actually supporting (since 1990) the "New geological map of Wallonia" research program, updating the former edition accomplished between ... [more ▼]

The regional governement of Wallonia (Région wallonne, DGARNE) is actually supporting (since 1990) the "New geological map of Wallonia" research program, updating the former edition accomplished between 1890 and 1919. The Walloon Region wants to enrich it by explicative works aiming to reach a large public like families, young people, etc... and to link physical activities to natural discoveries, in the respect of environment and nature. [less ▲]

Karst in granitic rocks, South Cameroon: Cave genesis and silica and taranakite speleothems

in Terra Nova (2002), 14(5), 355-362

A cave in granitic rocks was studied in Mezesse, South Cameroon. Coralloid speleothems, draperies and dissolution traces on the cave walls attest to its truly karstic nature. The speleothems consist of ... [more ▼]

A cave in granitic rocks was studied in Mezesse, South Cameroon. Coralloid speleothems, draperies and dissolution traces on the cave walls attest to its truly karstic nature. The speleothems consist of microlayers of opal and taranakite (K,NH4)Al3(PO4)3(OH).9H2O. They indicate a significant mobilization of silica, Al and K from granite during the formation of the cave. Identification of silicified bacteria in the speleothems layers suggests a possible role of these micro-organisms in silica deposition. The presence of taranakite and of silicified organic remains within the speleothems lead to a better understanding of the genesis of the cave. [less ▲]

The dynamics of the karstic features of Sprimont (Belgium) and its consequences on the land-use planning. Preliminary note.

in Proceedings of tne 12th International Congress of Speleology (1997)

The Department of Physical Geography of the University of Liège (Belgium) was in charge of updating the physical factors of the regional land management map for Sprimont, a karstic municipality of Belgium ... [more ▼]

The Department of Physical Geography of the University of Liège (Belgium) was in charge of updating the physical factors of the regional land management map for Sprimont, a karstic municipality of Belgium. The influence of floods, karst processes, landslides, and other physical factors were evaluated. The karst features and karst-related events have been mapped three times with accuracy in this area during the last century (in 1898, 1971 and 1996). The data provided the basis for a study of the rates and dynamics of the karst processes and permitted the forecasting of hazards on a secular basis. A map of karstic areas, karst features and karst dynamics was prepared. Some systematic trends of the evolution of karst features were noted. A map of risks and land-use constraints was derived from the first map and from the observed trends. Rules were induced from these data and were proposed to control building and other activities in clearly defined areas. [less ▲]