降水对广西马山兰电堂泉水化学动态变化观测研究

利用多参数自动记录仪(CDTP300)对广西马山兰电堂泉的降雨量、水位、水温、pH值和电导率进行自动化监测,数据采集间隔为15 min。结果发现,降雨期间泉水pH值和温度呈升高趋势的同时却出现电导率急剧降低的现象。通过进一步利用WATSPAC软件计算泉水方解石饱和指数(SI_C)、白云石饱和指数(SI_D)和二氧化碳分压(LogP-CO₂),发现其SI_C、SI_D和LogPCO₂值在降雨期间均呈明显降低趋势。由此可以推断,兰电堂泉水化学动态变化是由雨水的稀释作用造成的,因为研究区具有较高pH值和低电导率的雨水能够形成坡面流快速通过岩溶管道系统影响泉水的水化学性质,并使稀释作用成为控制表层岩溶泉在雨季水化学动态变化的主要因素。

Effect of precipitation on the hydrochemical variations in Landiantang spring at Nongla, Mashan, China

High-resolution measurements of rainfalls,water level,pH,conductivity and temperature in Landiantang epikarst spring at Nongla,Mashan county in Guangxi Province,China were recorded by using the data logger with time interval of fifteen minutes all the year round.And,the waters from the spring represent the exit for the aquifer's conduit flow.During the rainfalls,it was found that the pH and temperature of Landiantang spring increased and the conductivity reduced.As HCO~-_3,Ca~(2 ) and Mg~(2 ) were the dominant ions,we developed linear relationship between conductivity and those ions.According to the liner relationships,the calcite index(SI_C),the dolomite index(SI_D) and CO_2 partial pressure(LogPCO_2) of the spring were calculated.Results indicated that the LogPCO_2 of spring during rainfalls was lower than that without rain,and its SI_c and SI_D was also lower.By studying epikarst zone,it was known that above result was caused by the dilution of precipitation because rainfall with high pH and low conductivity forming slope stream and traveling through conduit rapidly affected the hydrochemical variations of epikarst spring.