Study on Variations of Speleothem and the Relationship Between SIC  and Precipitation in Furong Cave

Key words: 
• Furong Cave /
• speleothem /
• SIC /
• pH /
• PCO2 /
• precipitation

Abstract: Four monitoring sites were selected in Furong Cave, Wulong county of Chongqing China, including two drip water sites and two pool sites, respectively. The pH, temperature and concentration of HCO-3 in water for the four sites were tested in the cave, other water samples are analyzed in the laboratory for the concentration of some main ions (e.g. Mg2+, Ca2+, K+, Na+, SO2+4, etc.). Then the PCO2(Pressure of CO2) and the SIC (Saturation Index of calcite) were calculated with the WATSPEC software, the sediment of carbonate and the relationship between SIc and precipitation in Furong Cave were discussed. Some conclusions were drawn as follows: in most months of monitoring year, the water of the four sites is oversaturated to calcite, which reflected the stalagmites beneath them are in depositing. Activing sediments on a piece of glass which placed under one drip water in Furong Cave confirmed the results of the calculation of SIC. Furthermore, the SIC of drip water was usually higher than that of pool water in the same season. So the temperature and precipitation was well for the deposition in Furong Cave. And the unsaturated period also after the highrainfall month shows that the precipitation had a big effect on the SIC, so the highrainfall is the key factor for the deposition and lead to the alternate over saturation and unsaturation. 