关键词: 瑶琳洞, 风化碳酸钙景观, 复生试验

Abstract: The speleothem stability is threatened because it is seriously weathered and broken down as the cave environment is seriously effected by the tourism activities.The speleothem weathering is quite often in the show caves.Based on the laboratory experiments,the calcareous alkaline solution is the best one for the recovering experments.The field experiment work lasted one year.The calcareous alkaline solution was employed for the experiments to be dropped on the strong weathered stalagmite and flowstone with the slope of 45° and sprayed on the vertical column.The changes of conductivity, pH, Ca⁺² contents and alkalinity in the solution were monitored during the experiments.The results demonstrate that 98.9% of Ca⁺² was deposited in the distance of 1.5 m from the dropping point.pH values droped from 12.2 down to 8.5, OH-content decreased from 17.76 mg/l to 0 and the conductivity from 2 160 us/cm to 98.9 us/cm.After the experiments lasting for 3 month, the front side of the stalagmite was completely covered.The new stalactites, leaf pools and stone ears developed like the natural one.The scanning electronic microscope (SEM)is used to observe the crystal of calcite.The natural calcite performs the well trigonal crystals larger than 0.3 mm with perfect rhembohedral cleavage.The crystal of CaCO₃ deposited by the spaying solution is very similar to the natural one.The deposits by dropping are not so good as the spraying one, however, they have developed the trigonal crystals with the size of 15 μ-20μm even 35μm with good rhembohedral cleavage.The CaCO₃ deposit on the stalagmite has been changed to be hard to well protect the weathered speleothem.

Key words: recovering, weathered speleothem, Yaolin cave Zhejiang