喀斯特山区浅层地下水的季节变化特征及影响因素——以普定后寨河为例

Seasonal variation of shallow groundwater characteristics and their influence factors in karst mountains:A case study of the Houzhai River in Puding County

以贵州中部喀斯特山区普定县后寨河流域浅层地下水为研究对象,对浅层地下水的季节变化特征及影响因素进行分析。结果表明:在喀斯特山区,浅层地下水主要阴离子为HCO_3^-、SO_4^(2-)、Cl^-,分别占总离子含量的53%、15%、3%,主要阳离子为Ca^(2+)和Mg^(2+),占总离子含量的19%和6%,水化学类型为HCO_3^-Ca型水,pH为7.51~8.23,呈微碱性;浅层地下水具有明显的季节变化特征,HCO_3^-、Na^+、NO-3-N、Ca^(2+)、TP的季节差异显著(P<0.05),K^+、Mg^(2+)、Cl^-、TN、NH_4^+-N、SO_4^(2-)不同季节之间存在差异,但未达显著水平。喀斯特山区,浅层地下水化学性质主要由地层岩性决定,对农业活动、居民生活活动响应敏感,其中以农业活动最为显著,居民生活活动次之。喀斯特山区居民的农业活动和人为干扰使得浅层地下水中氮、磷质量浓度升高,明显影响水质。

This study focuses on the shallow groundwater of karst mountain areas in the Houzhai river in Puding county,Guizhou Province.Seasonal variations of characteristics and influence factors of shallow groundwater were analyzed.The results show that the shallow groundwater of this area contains main anion of HCO3^-,SO4^2-and Cl^-,accounting for 53%,15% and 3% of the total ion content,and main cation of Ca^2＋and Mg^2＋,accounting for 19%and 6% of the total ion,respectively.The hydrochemical feature is of HCO3^-Ca type water.The pH is between 7.51 and 8.23.The shallow groundwater has obvious seasonal variations in terms of hydro-chemical constituents,of which the contents of HCO3^-,Na^＋,NO3^--N,Ca^2＋and TP have significant seasonal differences（P0.05）,while those of K^＋,Mg^2＋,Cl^-,TN,NH4^＋-N and SO4^2-also seasonally fluctuate with the significant levels less than P0.05.The chemical properties of the shallow groundwater are affected in a combined way by agricultural activity,human disturbance and rock formation lithology,of which the most typical is agricultural activity,followed by human disturbance.These two impact factors have drastically elevated the N and P concentrations in shallow groundwater in the karst mountainous areas and as a result the water quality declined.