四川黄龙沟源头黄龙泉泉水及其下游溪水的水化学变化研究

用水化学仪器自动记录、现场滴定及取样室内分析等方法，对四川黄龙沟钙华景区水的物理化学动态变化特征进行了研究。结果发现，黄龙钙华的沉积主要起因于水中CO2的大量释放，造成溪流自黄龙泉泉口向下游方向水的二氧化碳分压（p（CO2））和电导率（EC）降低，pH值和方解石饱和指数（SIc）升高。但仔细分析发现，水化学的这一空间变化主要发生在SIc〈1．0时；当SIc〉1．0后，向下游方向，水化学趋于稳定。同时，黄龙沟地表融雪水和沿途泉水分别产生的稀释和浓集作用对溪流水化学的这一空间变化产生了明显的影响。此外，源头黄龙泉的水化学稳定，没有明显的日变化，而下游的池水则出现pH值、EC和SIc及p（CO2）的显著日变化，即白天p（CO2）、EC较低，而pH和SIc较高，反映了白天较快的碳酸钙沉积，其中温度和水生生物光合作用的影响可分别达到19％和81％。

Hydrochemical variations of Huanglong Spring and the stream in Huanglong Ravine, Sichuan Province

Methods of automatic hydrochemical logging and in situ titrating combined with indoor analysis were used to study the dynamic variation of the physicochemistry in Huanglong Ravine. It was found that the deposition of travertine was due to huge CO2 degassing from water, which leads to the decrease in p（CO2） and conductivity, and increase in pH and Sic from the Huanglong Spring to downstream. However, at Sic 〈 1.0, p（CO2） decreased and pH and Sic increased remarkably downstream, while at Sic 〉 1.0, p（CO2）, pH and Sic tend to be stable further downstream. Meanwhile, the downstream hydrochemical evolution was interrupted by the snowmelt water in the ravine through dilution effect, and the spring water downstream through concentrating effect. In addition, the chemistry of the Huanglong Spring is stable, without obvious diurnal variation. However, in the pools downstream, p（CO2） and EC are lower, and pH and Sic are higher at daytime than at nighttime. That means the deposition of travertine is quicker at daytime than at nighttime. It was concluded that this was caused by the combined influence of temperature and the aquatic photosynthesis, which contribute about 19% and 81%, respectively.