论文部分内容阅读
对洞穴次生碳酸盐沉积机理的认识是解释洞穴石笋气候环境指示意义的关键。近两个水文年的洞穴现代过程监测结果显示,万象洞内温湿度全年基本保持恒定;洞穴滴水的pH值夏季偏低、冬季偏高,呈现出一定的季节变化特征,电导率和HCO_3~-浓度及主要阴阳离子含量年内变化不显著;洞内CO_2分压夏季偏高,冬季降低接近于当地大气的CO_2分压水平。对不同滴水点的对比研究表明,滴水中Ca~(2+)达到一定浓度是方解石沉积的必要条件。此外,万象洞夏季CO_2分压的升高对方解石形成产生明显的抑制作用。万象洞石笋沉积的主要受控于滴水饱和度以及洞穴CO_2分压。
The understanding of the mechanism of secondary carbonate deposition in caves is the key to explain the significance of climate and environment in stalagmite caves. The monitoring results of modern process of caves in the past two hydrological years show that the temperature and humidity in Vientiane Cave are basically constant throughout the year. The pH value of cave drip is low in summer and high in winter, showing some seasonal variations. The conductivity and HCO 3 ~ - Concentration and major anion and cation contents did not change significantly during the year; the partial pressure of CO_2 in the cave was high in summer, and the partial pressure of CO_2 near the local atmosphere decreased in winter. The comparative study of different drip points showed that the Ca ~ (2+) concentration in drip irrigation is a necessary condition for calcite deposition. In addition, the increase of CO 2 partial pressure in summer in Vientiane cave significantly inhibited calcite formation. The deposition of stalagmite in Vientiane Cave is mainly controlled by the drip water saturation and the partial pressure of CO 2 in the cave.