石漠化地区洞穴滴水地球化学特征——以贵州省石将军洞为例

Geochemistry of Drip Water in Cave of Rocky Areas——A Case Study of Shijiangjun Cave in Guizhou Province

为探讨石漠化条件下岩溶洞穴滴水水化学特征及其对地表环境的指示意义,选取贵州省安顺市具有强烈石漠化特征的石将军洞进行为期1年的动态监测,并对该洞穴8个滴水点滴速及元素质量浓度进行分析,根据各滴水点滴速季节变化稳定性将滴水点分为2种类型:1快速型,岩层薄,滴速不稳定.2平缓型,岩层厚,滴率季节变化平缓,受到降水影响小;各月滴水记录的元素质量浓度呈现一致的空间变化规律,季节变化小.石漠化地区土薄石厚,滴速主要受到岩石裂隙的控制,水-岩作用的程度控制洞穴滴水的变化.石将军洞位于强度石漠化地区,土壤层薄,涵养水源能力不足,导致石将军洞滴水pH值呈现"旱季低雨季高"的异常现象,而非受大气降水季节性变化的影响;石将军洞滴水Mg/Ca比值呈现旱季高雨季低的规律;对比2个不同石漠化程度洞穴的Ca2+,Mg2+等元素质量浓度以及EC,发现:气候条件完全一致的2个洞穴,轻度石漠化洞穴本寨洞Ca2+,Mg2+质量浓度、EC以及变化幅度都高于石将军洞.总之,石漠化地区洞穴理化特征变化主要驱动因子来自于本身洞穴体系,而并非直接的外界气候条件.

This paper deals with 8 drip points monitored yearly in the Shijiangjun cave ,Anshun County of Guizhou Province ,to investigate the chemical characteristics and its implications for the surface environ-ment of karst cave dripping water .The drip point response to seasonal changes of precipitation at different speeds .The drip point precipitation responds basically are divided into two types ：（1） fast type .It has close relationship with seasonal precipitation change .（2） flat type .Shijiangjun cave which located in se-vere rocky area of Anshun country .The element concentrations of drip water records for each month showed a consistent spatial variation that exists small seasonal change .Because there exists thin soil and huge rock in rocky desertification area ,the drip rate is mainly controlled by rock fractures .Soil layer is so thin that can not conserve water ,nitrogen fertilizer and other agricultural residues infiltrate into the car-bonate rocks fractures rapidly with precipitation during the rainy season .Above all ,pH value is low in wet season and high in dry seasons which are different from normal cave pH research .To some extent ,Shi-jiangjun drip water is not controlled by precipitation .Mg/Ca ratio shows that it is high in dry season and low in wet season .Comparing the Ca^2＋ ,Mg^2＋ ,EC concentration in Shjiangjun cave with Benzhai cave . The results show that Ca^2＋ ,Mg^2＋ ,EC concentration is higher in Benzhai cave （mild rocky desertification） than Shijiangjun cave （severe rocky desertification ） .It is suggested that the Ca^2＋ ,M g^2＋ ,EC concentration may be controlled by the coverage of vegetation .