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利用多参数自动记录仪对桂林岩溶试验场的降水量、水位、水温、pH值和电导率进行了监测,数据采集间隔根据参数变化的程度由2min到1h不等。结果发现,岩溶裂隙水在洪水期间pH值呈降低趋势,而电导率呈升高的不寻常变化。与此相反,对于岩溶管道水,同样是在洪水期间,它的pH值是升高的,而电导率呈正常的降低。考虑到Ca2+和HCO-3分别为地下水中主要的阴阳离子(>90%),及它们与电导率的线性关系,计算得到了洪水期间方解石的饱和指数(SIc)和水的CO2分压(Pco2)的变化情况。发现洪水时裂隙水的Pco2高于正常情况的Pco2,而它的SIc值比正常情况低。与此相对,对于管道水,尽管同一洪水期间其SIc降低,但Pco2也降低。从这些结果,可以推断,至少有两个关键的过程控制着洪水期间的水化学变化。一个是雨水的稀释作用,另一个是水-岩-气的相互作用。然而,对于裂隙水来说,后者的作用可能更重要,即在洪水期间,高浓度的土壤CO2溶解于水中,则更具侵蚀性的水能溶解更多的石灰岩,从而增强水的电导率。而对于管道水,雨水的稀释作用更重要,因为研究区较高的pH和低电导率的雨水能更快地通过管道流出,所以,要了解岩溶系统水化学的变化,仅考虑水-岩相互作用是不够的,我们还必须重视CO2气体对岩溶系统中水化学变化的影响。总之,水-岩-气相互作
The rainfall, water level, water temperature, pH value and conductivity of Guilin karst test site were monitored by using multi-parameter automatic logger. The interval of data collection varied from 2min to 1h according to the parameter variation. The results show that the pH value of karst fissure water decreases during the flood period, while the conductivity shows an unusual change of increasing. In contrast, for karst pipe water, also during flooding, its pH increases and its conductivity decreases normally. Considering that Ca2 + and HCO-3 are the major cation and cation (> 90%) in groundwater and their linear relationship with conductivity respectively, the saturation index (SIc) of calcite and partial pressure of water CO2 ) Changes. The Pco2 of fissure water was found to be higher than Pco2 at normal conditions in floods and its SIc value was lower than normal. In contrast, Pco2 also decreases for plumbing despite a decrease in its SIc during the same flood. From these results, it can be inferred that at least two key processes control the chemical changes in water during the flood. One is the dilution effect of rainwater and the other is the water-rock-gas interaction. However, the role of the latter may be more important for fissure water, where high concentration of soil CO2 dissolves in the water during the flood, and more aggressive water dissolves more of the limestone and thus enhances water conductivity . The dilution effect of pipeline water and rainwater is more important because the higher pH and low conductivity rainwater in the study area can flow out more quickly through the pipeline. Therefore, to understand the change of water chemistry in karst system, only water-rock interaction The role is not enough, we must also pay attention to CO2 gas karst water chemistry changes in the impact. In short, water - rock - gas interaction