土壤CO2、土壤水的动态特征及其 对岩溶作用的驱动

为了研究不同土壤CO2浓度和不同土壤水化学条件下的岩溶作用发生程度，文章对广西桂林地区的土壤CO2浓度、土壤水和石灰岩试片溶蚀速率进行了监测，结果表明：1）该地区土壤CO2浓度具有明显的季节性变化特征，总体上夏季是其他季节的3~5倍，最大值时达到60 899.64 mg/m2，而最小值时仅为5 587.21 mg/m2；2）就相同深度的土壤CO2浓度来说，洼地大于坡地，夏季时洼地比坡地高近20 000 mg/m2，且深层土CO2浓度大于表层土，其平均值比表层土高4 353.54 mg/m2；3）坡地和洼地土壤水水化学指标平均值分别是：pH为7.49和6.41、电导率为300和78 μS/cm、Ca2+为60和15.43 mg/L、 为2.78和0.44 mg/L，坡地处的pH、电导率、Ca2+和 均高于洼地；4）从溶蚀试验说明该地区的岩溶作用发生程度非常明显，说明土壤CO2和土壤水能驱动岩溶作用的发生。

Dynamic Characteristics of the Soil CO2 and Soil Water Chemistry, and Their Driving Action on Karstification

In order to understand the occurrence degree of karstification under different soil CO2 concentration and soil water chemistry, the soil CO2 concentration, water content and erosion rate of limestone were monitored in the area of Guilin, Guangxi Province.The results showed that: (1)The soil CO2 concentration had seasonal variation obviously with a trend of that the highest in summer and the lowest in winter, the soil CO2 concentration in summer was 3~5 times as many as those in other seasons on the whole, the maximum was 60899.64 mg/m2, while the minimum only 5587.21 mg/m2; (2)The CO2 concentration in the soil of depression was higher than that in the soil of slope at the layers of the same depth, the former was nearly 20 000 mg/m2 more than that of the latter in summer, and the concentration was higher at deep layer than that at surface, and the mean value was 4353.54 mg/m2 more than the concentration at surface; (3) The average values of soil water chemistry in the soil of slope and depression were as follows: pH 7.49 and 6.41, conductivity 300 μS/cm and 78 μS/cm, Ca2+ 60 mg/L and 15.43 mg/L, 2.78 mg/L and 0.44 mg/L, respectively; the pH value, conductivity, Ca2+ and in soil water of slope were all higher than those of the depression; (4) Corrosion test indicated that the Karstification was very obvious in the study area, and was closely related to soil CO2 and soil water. So it is concluded that the karstification was driven by soil CO2 and soil water.