Influence of Pedo-chemical Field on Epi-karstification in Subtropical Humid Region-Field Monitoring and Laboratory Experiment
Genxing Pan, Yuxiang Tao , Yogzhong Teng , Shenyou Xu , Yuhua Sun , Fushun Han - (27/1,1998)
The influence of pedo-chemical conditions on epi-karstification in a karst hydrogeochemical experiment site near Guilin was studied. The dissolution of limestone, and pH, CO2, HCO3- in soil and karst water under soil cover conditions was monitored by using filter tubes containing reference rock plate, and by using portable pH meter, CO2 gas meter and Aqumerck Kit. Laboratory experiments of dissolution under different soil conditions were also conducted by using leaching cylinders. In addition, 13C tracing was carried out on the samples of plant- litter- SOM-soil CO2-spring water-travertine-rock in the karst system. Soil pH, SOM status (subsequently CO2 concentration) and Ca+2 saturation constitutes a pedo-chemical field vigorously affecting the rock dissolution. The carbon in the form of HCO3- in the spring water and of CaCO3 in the travertine was closely related with the soil CO2 gas. Thus, soil carbon through the transferring pathway of air CO2-plant carbon-SOC-soil CO2 was involved in the epi-karstification process, and interface exchange of soil Ca+2, HCO3- with karst water existed in the karst hydrogeochemical flow. A modified model for epi-karstification in the studied area was suggested.