重庆芙蓉洞上覆泉水—滴水的氢氧稳定同位素变化研究

Study on Characteristic and Significance of Hydrogen and Oxygen Isotope Changes of Overlying Spring-drip of Furong Cave in Chongqing

通过对重庆芙蓉洞上覆泉水、洞穴滴水的氢氧稳定同位素和气象要素的系统监测,发现芙蓉洞滴水主要来源于当地大气降水,洞穴滴水稳定同位素变幅远小于上覆泉水。其中滴水与泉水的δ18O变幅分别在-7.7‰～-6.8‰和-12.4‰～-4.7‰之间。洞穴滴水和岩溶泉水之间并未出现协调的季节变化规律。另外重庆地区10月份降水状况对上覆泉水稳定同位素影响明显。分析表明洞穴系统上覆基岩的厚度和包气带含水层的调蓄作用对洞穴滴水的同位素不变化影响巨大,平滑了其中的月季变化信息,在利用洞穴沉积物重建高精度古气候信息要对其格外注意。

Based on the systematic monitoring of overlying spring, the hydrogen and oxygen isotope and the meteorological factors of Furong Cave in Chongqing, it is found that the source of the drip of Furong Cave is the local precipitation and the fluctuation of its stable isotope is less than the overlying spring. The ranges of oxygen isotope of drip and overlying spring is - 7.7‰ - 6.8‰ and - 12.4‰ - - 4.7‰ respectively. And the changes of the drip and overlying spring have little rele- vance to seasonal changes. Besides, in October, the precipitation in Chongqing has great influence on stable isotope of overly- ing spring. The analytic result proves that the sickness of overlying bedrock of the cave system and storage of aeration zone aq- uifer has enormous influence on the drip＇ s isotope, which smoothes the monthly and quaternary changes. The conclusion is that much caution should be paid on this during reconstructing high precision paleoclimate.