Dogwiler Toby and Wicks Carol 2006. Thermal Variations in the Hyporheic Zone of a Karst Stream.
International Journal of Speleology, 35 (2), 59-66. Bologna (Italy). ISSN 0392-6672.
Re-published from: Speleogenesis and Evolution of Karst Aquifers 3 (1), http://www.speleogenesis.info/, 11 pages (ISSN 1814-294X).
This investigation quantifies how temperatures in the streambed sediments of a karst stream fluctuate in relation to discharge, seasonal, and diurnal temperature variations as the stream passes through a karst window. Furthermore, the linkages between meteorological processes and temperature variation in the hyporheic zone are delineated. Examination of a high-resolution, three dimensional record of temperature variation in a karst stream substrate provides insight into thermal disturbances in the hyporheic zone. Temperatures in the upper portion of the hyporheic zone are strongly linked to air temperatures via the surface water. The variation is considerably less as depth increases. The annual temperature variation in the lower portion of the shallow hyporheic zone is reduced by one-third, relative to the variation observed in the surface water and upper substrate. During storm events, the upper portion (0-5 cm) of the shallow hyporheic zone is subject to a thermal regime very similar to surface stream water. However, below these depths the sharpest temperature fluctuations are effectively muted within the stream substrate. More frequent diurnal variations, particularly those associated with baseflow conditions, are also dampened within the substrate.
Onac Bogdan P., Zaharia Luminiţa, Kearns Joe and Veres Daniel 2006. Vashegyite from Gaura cu Muscă Cave.
International Journal of Speleology, 35 (2), 67-73. Bologna (Italy). ISSN 0392-6672.
Paper presented during the 14th International Congress of Speleology, Kalamos (Greece) 21-28 August 2005.
This study investigated the occurrence of vashegyite from a guano-rich deposit located in the Gaura cu Muscă Cave, Romania. Analytical methods used include optical microscopy, X-ray powder diffraction (XRD), scanning electron-microscopy (SEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), thermal investigations and Fourier-transform infrared (FT-IR) analyses. Vashegyite occurs as friable, chalky white, irregular nodules of up to 2.5 cm in diameter, within a 15 cm thick sequence of organic and minerogenic sediments. The chemical structural formula is:
(Al10.91Fe3+ 0.06Na0.1Ca0.02Mg0.08)Σ=11.17[(PO4)8.78(SiO4)0.056]Σ=8.83(OH)6.17·43.79H2O.
Electron microscope images show vashegyite crystals to be flattened on (001). The orthorhombic lattice constants of vashegyite determined by XRD are a = 10.766(2) Å, b = 15.00(4) Å, c = 22.661(1) Å, and V = 3660.62 Å3 (Z = 4). The major weight loss, reflected in 3 endothermic peaks, was observed between 40° and 200°C, corresponding to the removal of water molecules. Vashegyite FT-IR absorption bands are comparable in position and relative intensity to other Al-phosphates. Water percolating through guano becomes strongly acidic and reacts with the clay-rich sediment laid down by the underground stream to form vashegyite. In the lower part of the investigated profile, crandallite and ardealite were also found.
de Freitas Chris R. and Schmekal Antje Anna 2006. Studies of Condensation/Evaporation processes in the Glowworm Cave, New Zealand.
International Journal of Speleology, 35 (2), 75-81. Bologna (Italy). ISSN 0392-6672.
Re-worked from: Speleogenesis and Evolution of Karst Aquifers 3 (2), http://www.speleogenesis.info/, 11 pages (ISSN 1814-294X).
The condensation/evaporation process is important in caves, especially in tourist caves where there is carbon dioxide enriched air caused by visitors. The cycle of condensation and evaporation of condensate is believed to enhance condensation corrosion.
The problem is condensation is difficult to measure. This study addresses the problem and reports on a method for measuring and modelling condensation rates in a limestone cave. Electronic sensors for measuring condensation and evaporation of the condensate as part of a single continuous process of water vapour flux are tested and used to collect 12 months of data. The study site is the Glowworm tourist cave in New Zealand. The work describes an explanatory model of processes leading to condensation using data based on measurements of condensation and evaporation as part of a single continuous process of water vapour flux.
The results show that the model works well. However, one of the most important messages from the research reported here is the introduction of the condensation sensor. The results show that condensation in caves can actually be measured and monitored, virtually in real time. In conjunction with the recent developments in data logging equipment, this opens exciting perspectives in cave climate studies, and, more generally, in hydrogeological studies in karst terrains.
Lauriol Bernard, Prévost Clément and Lacelle Denis 2006. The distribution of diatom flora in ice caves of the northern Yukon Territory, Canada: relationship to air circulation and freezing.
International Journal of Speleology, 35 (2), 83-92. Bologna (Italy). ISSN 0392-6672
In the late 1980’s and early 1990’s, various mediums in karst environments in the Northern Yukon Territory were examined for their diatom content. Cryogenic cave calcite powders, grus and various ice formations (ice plugs, ice stalagmites and floor ice) were collected from three freezing caves and one slope cave to make an inventory of the diatom content, and to explain the spatial distribution of the diatoms within the caves. The results show that approximately 20% of diatoms in caves originate from external biotopes and habitats (e.g., river, lake, stream), with the remaining 80% of local origin (i.e., from subaerial habitats nearby cave
entrances). The results also indicate that the greater abundance of diatoms is found in the larger caves. This is explained by the fact that the air circulation dynamics are much more important in caves that have a larger entrance. Also we have noticed that grus, ice plugs and ice stalagmites have lowest diatom diversity, but greater relative abundance, indicative of growth in specific habitats or under specific conditions. Overall, these results are a contribution to the study of particles transport in caves and in particularly ice caves.
Craven Stephen A. and Smit Berend J. 2006. Radon in caves: clinical aspects.
International Journal of Speleology, 35 (2), 93-101. Bologna (Italy). ISSN 0392-6672
Historical, experimental and clinical evidence is presented to suggest that radon constitutes a relatively small carcinogenic risk for casual visitors to caves. The risk is dependent on radon levels and the smoking of tobacco. Show cave guides, chronically exposed to radon, may be at increased risk for lung cancer due to the effects of radon, especially if they are smokers of tobacco.
White William B. 2006. Identification of cave minerals by Raman spectroscopy: New technology for non-destructive analysis.
International Journal of Speleology, 35(2), 103-107. Bologna (Italy). ISSN 0392-6672
Paper presented during the 14th International Congress of Speleology, Kalamos (Greece) 21-28 August 2005.
The identification of minerals from caves generally requires that samples be removed from the cave for analysis in the laboratory. The usual tools are X-ray powder diffraction, the optical microscope, and the scanning electron microscope. X-ray diffraction gives a definitive fingerprint by which the mineral can be identified by comparison with a catalog of reference patterns. However, samples must be ground to powder and unstable hydrated minerals may decompose before analysis is complete. Raman spectroscopy also provides a fingerprint useful for mineral identification but with the additional advantage that some a-priori interpretation of the spectra is possible (distinguishing carbonates from sulfates, for example). Because excitation of the spectra is by means of a laser beam, it is possible to measure the spectra of samples in sealed glass containers, thus preserving unstable samples. Because laser beams can be focused, spectra can be obtained from individual grains. New technology has reduced the size of the instrument and also the sensitivity of the optical system to vibration and transport so that a portable instrument has become possible. The sampling probe is linked to the spectrometer by optical fibers so that large specimens can be examined without damage. Comparative spectra of common cave minerals demonstrate the value of Raman spectra as an identification technique.
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