喀斯特山地不同土地利用对表层岩溶泉水化学特征的影响

Effects of Land Use Patterns on Hydrochemistry of Epikarst Springs in Karst Mountains Area

选取南川喀斯特山地3种不同土地利用方式(灌草丛、耕地、石漠化地)下的表层岩溶泉水为研究对象,通过对3个泉水进行一个水文年的水温(t)、pH、电导率(EC)、HCO3-、NO3-、SO42-、Cl-、Ca2+、Mg2+、Na+、K+等水化学指标的测定,结果发现:3个泉水的t、pH、EC及主要阴阳离子都表现出了一定的差异,在t、EC及NO3-、SO42-、Cl-、Na+浓度上,表现为灌草丛泉水<耕地泉水<石漠化地泉水,在K+浓度上,表现为耕地泉水>石漠化地泉水>灌草丛泉水。3个泉水HCO3-+Ca2+占所测9种主要离子的比例分别为87.1%,71.8%,62.9%。泉水的HCO3-浓度及HCO3-+Ca2+占所测定的9种主要离子的比例由灌草丛泉水→耕地泉水→石漠化地泉水逐渐减少。这说明EC、NO3-、SO42-、Cl-、Na+、HCO3-等泉水水化学指标可以作为不同土地利用方式和植被覆盖变化的重要指标。

Epikarst spring is the important source of drinking water and irrigative water in Karst mountains area.The hydrochemistry of the epikarst springs varies obviously under various land use patterns.Water temperature,pH,EC,major anions（HCO3^-、NO3^-、SO4^2- and Cl^-） and major cations（Ca^2＋,Mg^2＋,Na^＋ and K^＋） of three epikast springs,which shared the same climatic condition but under different land use patterns（shrud-grass land,agricultural land and rocky desertification land） at Nanchuan,Chongqing province,were monitored during the hydrological year from November,2007 to October,2008.The results showed that the hydrochemistry of epikarst springs exhibited an obvious variation.Water temperature,pH,EC and major ions in springs all exhibited obvious variations.Under the order of land use patterns from shrud-grass land,agricultural land to rocky desertification land,pH,EC and the contents of NO3^-,SO4^2-,Cl^-,Na^＋ were significantly enhanced,while the content of HCO3^- and the percentage of HCO3^-＋Ca^2＋ were decreased.And that the contents of K^＋ decreased from the agricultural land,rocky desertification land to shrud-grass land.With the change of land use patterns and reduction of vegetation coverage,the purification and water conservation of soil decreased.At the same time,the contents of the major ions in epikarst springs were significantly enhanced.Therefore,all these indicated that the Karst hydrochemical parameters,e.g.,electronic conductivity,NO3^-,SO4^2-,Cl^-,Na^＋,HCO3^-,could serve as indicators of different land use patterns and land covering changes.And during the processes of protecting water resource and water environment,it had important significance to considering the changes of land use.