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对重庆青木关岩溶槽谷区内一条地下河的pH值、电导率、HCO3-、Ca2+、SO42-、Mg2+以及NO2-、NO3-等水化学指标进行了7个月至1年不等的监测,这些指标在空间和时间分布上具有不同特征.在空间上,电导率及HCO3-、Ca2+、Mg2+、NO3-浓度自地下河上游至下游逐步升高,比较地下河入口(D1)和出口(S2)处,电导率升高100μS/cm,HCO3-浓度升高1.5 mmol/L,Ca2+浓度升高17 mg/L,Mg2+浓度升高5.1 mg/L,NO3-浓度相差6.4倍,而pH值和SO42-浓度则呈逐渐降低的趋势,D1和S2处的pH值相差0.16,SO42-浓度相差26 mg/L.在时间分布上,pH、电导率、HCO3-、Ca2+、SO42-、Mg2+浓度季节变化明显,夏、秋季的值比冬、春季低.NO2-、NO3-浓度变化在6、7月份有明显升高—回落的过程.对以上指标的影响因素分析显示:地质背景对水化学的控制、降雨的稀释效应、地下河的不同补给来源、岩溶作用的强弱程度以及农业活动的影响.
The pH value, conductivity, HCO3-, Ca2 +, SO42-, Mg2 +, NO2-, NO3- and other water chemical indicators of an underground river in the karst valley area of Qingmuguan in Chongqing were monitored for 7 months to 1 year , These indicators have different characteristics in space and time distribution. In space, electrical conductivity and HCO3-, Ca2 +, Mg2 + and NO3- concentrations gradually increase from upstream to downstream of the underground river, comparing the underground river inlet (D1) and outlet S2), the conductivity increased by 100μS / cm, the concentration of HCO3- increased 1.5 mmol / L, the concentration of Ca2 + increased 17 mg / L, the concentration of Mg2 + increased 5.1 mg / L and the concentration of NO3- And the concentration of SO42- decreased gradually, the difference of pH value between D1 and S2 was 0.16 and the difference of SO42- concentration was 26 mg / L. In the time distribution, pH, conductivity, HCO3-, Ca2 +, SO42-, Mg2 + The seasonal changes were obvious, the values in summer and autumn were lower than those in winter and spring.The changes of NO2- and NO3- concentrations in June and July were obviously increased-decreased.The analysis of the influencing factors of the above indicators showed that: The dilution effect of rainfall, the different supply sources of underground rivers, the degree of karstification and the impact of agricultural activities.