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采用CTDP300多参数水质自动记录仪对重庆市南山老龙洞地下河出口处的地下水在降雨条件下水位、水温、pH值和电导率进行监测,以及2h时间间隔的地下水水化学指标(HCO3-,Ca2+,Mg2+,NO3-,PO34-,SO24-,Fe2+,Mn2+,Ba2+)测定,根据监测数据进行分析对比,结果表明:监测期间南山老龙洞地下河水质变化与降雨、气温以及流量表现出良好的响应关系,降雨前后水质变化明显,这可能是因为降雨的稀释作用以及大流量、快流速使水体中CO2由于水体的扰动逸出,导致HCO3-质量浓度低.随后由于降雨停止,HCO3-质量浓度升高.可能与此时的水受到来自岩溶洼地水和来自裂隙水的补给有关,并且HCO3-与水温的关系为负相关.Ca2+与Mg2+质量浓度在降雨初期随降雨量的增多而减小,之后开始上升,与雨水的稀释有关,但是其最高值不在降雨量的最大值.NO3-,PO34-,SO42-的质量浓度随降雨的到来和流量的增加而升高.Fe2+,Mn2+,Ba2+质量浓度在降雨初期迅速上升,Mn2+在降雨过后,快速下降.降雨初期,各种离子的变化受雨水稀释作用控制,降雨停止后,表层岩溶带的高裂隙率和渗透性开始发挥作用,水动力条件和CO2效应占主导,进而影响水质的变化.
The water level, water temperature, pH value and conductivity of groundwater at the exit of Laolongdong underground river in Nanshan of Chongqing Municipality were monitored by CTDP300 multi-parameter automatic water quality recorder. The chemical indicators of groundwater (HCO3-, Ca2 + , Mg2 +, NO3-, PO34-, SO24-, Fe2 +, Mn2 +, Ba2 +) were measured and compared with the monitoring data. The results showed that the water quality change of Laolongdong underground river during the monitoring period showed good response to rainfall, temperature and flow The relationship between water quality before and after rainfall changes obviously, which may be due to the dilution effect of rainfall and the large flow rate and fast flow rate, which cause the CO2 in the water body to escape due to the disturbances of the water body, resulting in a low concentration of HCO3-, followed by the stop of rainfall, Which may be related to the fact that water is replenished from karst depressions and fissure water at this time, and the relationship between HCO3- and water temperature is negatively correlated, and the mass concentrations of Ca2 + and Mg2 + decrease with the rainfall at the beginning of rainfall Began to rise, with the dilution of rainwater, but its maximum value is not the maximum rainfall .NO3-, PO34-, SO42- mass concentration with the arrival of rainfall and rising flow High.The concentrations of Fe2 +, Mn2 + and Ba2 + increased rapidly at the beginning of rainfall, and Mn2 + decreased rapidly after the rainfall.The variation of various ions was controlled by the dilution of rainwater at the beginning of rainfall, and after the rainfall stopped, the high fracture rate and permeation of epikarst zone Sex begins to play a role, with hydrodynamic conditions and CO2 effects dominating, which in turn affects changes in water quality.