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以桂林附近岩溶水文地球化学试验场为基点研究了土壤化学条件对岩溶的影响 ,分别用砂滤管法、便捷式 pH计及CO2 浓度计及水化学简易测定在野外监测了岩石试片的溶解 ,土壤覆盖条件下土壤及岩溶水pH、CO2 浓度及HCO-3 浓度。用淋溶柱法实验室模拟了不同土壤覆盖下岩石试片的溶解。对岩溶系统中植物—凋落物—土壤有机质—土壤CO2 —岩溶水HCO-3 —钙华—岩石的13 C进行了采样和分析。结果表明 ,土壤pH、土壤有机质 (由此影响CO2 浓度 )及Ca2 + 饱和度构成影响岩溶活动的土壤化学场。岩溶水HCO-3 和钙华CaCO3 中的C与土壤CO2 —C密切相关。因此 ,岩溶过程涉及土壤发生性碳的作用 ,它通过大气—植物—有机质—土壤CO2 —岩溶水HCO-3 而在系统中转移 ,岩溶水文地球化学流中存在土壤Ca2 + 与岩溶水的界面交换。据此提出了研究区表层岩溶碳转移模式。
The effect of soil chemical conditions on karst was studied on the basis of karst hydrogeochemical test field in Guilin. The dissolution of rock samples was monitored in the field using sand filter, portable pH meter, CO2 concentration meter and water chemistry simple test Soil pH, CO2 concentration and HCO-3 concentration of soil and karst water under soil cover conditions. The leaching column method was used to simulate the dissolution of rock specimens under different soil cover. The 13 C of plant-litter-soil organic matter-soil CO2-karst water HCO-3-travertine-rock in the karst system was sampled and analyzed. The results show that soil pH, soil organic matter (thus affecting CO2 concentration) and Ca2 + saturation constitute the soil chemical field that affects karst activity. C in karst water HCO-3 and travertine CaCO3 is closely related to soil CO2-C. Therefore, the karst process involves the role of soil-forming carbon in the system through atmospheric-plant-organic matter-soil CO2-karst water HCO-3. There is an interface exchange between soil Ca2 + and karst water in the karst hydrogeochemical flow . According to this, the model of epikarst carbon transfer in the study area is proposed.