engleski

Physical research in Croatia's deepest cave system Lukina jama-Trojama, Mt.Velebit

The objective of this study is to present the first results of research conducted in the 1421 m deep cave system Lukina Jama during 2010 and 2011. The cave is situated in the area of Hajdučki kukovi in Northern Velebit National Park (Croatia) and is the deepest cave system in the Dinaric karst. In situ measurements of microclimate parameters and radon concentrations were performed at 20 measuring points. Two temperature gradients were detected: dT/dh = -3.65 ± 0.3oC/100 m from the entrance to a depth of 200 m and dT/dh = +0.39 ± 0.04oC/100 m to the bottom of the cave. Ice and snow dynamics influenced microclimate parameters to a depth of 200 m. Mean radon concentrations changed with distance, from 200–600 Bq/m3 in the upper cave sections, to 1139 Bq/m3 in the lower sections. This increase is in correlation with the partial pressure of carbon dioxide, which is an important factor in a variety of geochemical processes occurring in caves. Speleothems occur rarely in the deep caves of Mt. Velebit, and therefore the microclimate and geological conditions at the locations where they occur. As reported here, microclimate conditions below a depth of 220 m to the bottom are very stable, so speleothems are good candidates for further paleoclimate investigation.

cave microclimate ; radon ; deep pits Lukina jama ; Velebit Mt. ; Croatia

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