典型喀斯特表层岩溶带地下水化学特征——以贵州清镇王家寨喀斯特小流域为例

The hydrochemical characteristics of the epikarst zone:a case study on Wangjiazhai karst catchment in Qinzhen city,Guizhou province

以喀斯特小流域为研究尺度,对清镇市王家寨退耕还林(草)示范区内的9个表层岩溶泉进行了一个水文年的系统监测,并借助SPSS统计软件开展了泉点的聚类分析研究,旨在从常规水化学角度为流域退化生态环境的恢复与重建提供科学依据。从结果来看,虽然所有泉点的水化学类型均为HCO3-Ca型,但是根据K+、Na+、Ca2+、Mg2+、F-、Cl-、NO3-、HCO3-、SO42-等指标的具体差异,还是可以将9个泉点分为3组:(1)位于流域上游分水岭处的S8、S9泉点,由于远离居民集聚区,受到人类活动的影响程度弱,泉水中EC和各主要离子的质量浓度均很低,[Ca2+]*与[HCO3-]的关系说明泉水流经地区的岩石类型主要为白云岩;(2)位于流域中部的S2、S3、S4、S5、S6和S7泉点,靠近居民点,受到人类活动的影响程度明显增强,泉水中EC和各主要离子的质量浓度也相应增大,[Ca2+]*与[HCO3-]具有与第一组泉水完全不同的特征,表明此组泉水流经地区的岩石类型为白云质灰岩;(3)位于流域下游的S1泉点,处于村寨下游,受到人类活动的影响最大,泉水中EC和各主要离子的质量浓度也很高,[Ca2+]*与[HCO3-]的关系与第二组泉点相似,但是[SO42-]和[F-]远高于前2组泉点,这可能是由于在泉水的运移路径上有富含石膏和氟的岩石存在。

In this paper,we monitored 9 epikarst springs for a hydrological year in Wangjiazhai of Qinzhen City in Guizhou Province,where farmlands were converted to forestry and pasture,and carried out a clustering analysis with SPSS statistical software from the perspective of conventional water chemistry to provide scientific bases for the restoration and reconstruction of degraded watershed.From the results,although the types of water chemistry of all springs were HCO3-Ca,the 9 springs could be divided into 3 groups according to the specific differences in indicators like K＋,Na＋,Ca2＋,Mg2＋,F-,Cl-,NO3-,HCO3-and SO42-（1） S8 and S9 on upper watershed and free from the influence of human activities,where EC and the concentration of major ions in springs were very low and the relationship between [Ca2＋] ＊and[HCO3-] demonstrated that the region consisted mainly of dolomite rocks.（2） S2、S3、S4、 S5、S6 and S7 on middle watershed and near residential areas,where EC and the concentration of major ions in springs were high and the relationship between [Ca2＋]＊ and [HCO3-] was different from that in group 1,demonstrating a transition of rock types from dolomite rocks to imestones.（3） S1 on lower watershed and highly influenced by human activities,where EC and the concentration of major ions in springs were very high,the relationship between [Ca2＋]＊ and [HCO3-] was similar to that of group 2,but [SO42-] and [F-] were higher than those in the other groups,demonstrating the possible existence of rocks rich in gypsum and fluorine in the migration path.