The Study of Recent Destructive Processes in the Moravian Karst Caves (czech Republic)

This work tried to decide whether an occasionally observed falling of straw stalactites in the Moravian Karst caves is caused by a hypothetical chemical corrosion. The straw stalactite wall was found to be formed by three calcite layers. The middle layer (a stalactite skeleton) was typically cracked in agreement with calcite cleavage. Some impact of chemical corrosion was positively identified on the outer side of straw stalactite walls. Any corrosion of the inner wall of stalactite channel was not explicitly proved. This is consistent with the supersaturation of the majority of monitored dripping waters with respect to calcite (SI=0.2 to 1.2). However, the finding of unsaturated dripping water in the Punkevní Caves (SI=-0.8 to -0.3) did not allow to exclude the chemical corrosion definitively. The seasonal increase of cave CO2-concentrations (up to 1 vol. %) was consistent with increasing number of visitors (up to 28 000 per month in the Punkevní Caves) and with the CO2-production in the soils above caves (up to 1 vol. % in soil atmosphere in Summer). The drop of the cave CO2-concentrations in Fall and Winter roughly corresponds to the decrease of the soil CO2-concentration, visitor number, and probably also to change in cave ventilation. Enhanced concentrations of NO3 in the Amatérská Cave (up to 1.2x10 mol/l) indicate anthropogenic pollution.