天然荧光物质作为岩溶地下水的示踪剂研究——以湖北清江和尚洞为例

Natural fluorescent substance as tracer for karst groundwater—A case study on Heshangdong of Qingjiang,Hubei

天然荧光物质作为岩溶地下水的示踪剂的相关报道较少。在详细研究了湖北清江和尚洞岩溶滴水中荧光物质的光谱特征及其季节变化的基础上,探讨了天然荧光物质作为岩溶示踪剂的可行性。研究结果表明,和尚洞岩溶滴水中的主要荧光物质是富里酸,其特征波长对为:激发波长304nm,发射波长407nm。在年季旋回中,荧光强度与滴水的氧同位素组成有一致的季节变化(r=0.539,p>0.99)。滴水1δ8O和荧光强度峰值(5月,初夏)出现明显滞后于补给水(冬季降水),两者的时间差指示了岩溶水的滞留。因此,天然荧光物质作为一种新型的地下水的示踪剂,具有灵敏、经济及环保等特点,特别适合源头未知的岩溶水示踪。

Being highly sensitive and friendly to environment, the method of using natural tracer has been widely used in karst water researches, while using fluorescent substance as tracer is rarely involved nowadays that is highlighted in this paper. Here we investigated spectrum characteristics and seasonal variations of the nature fluorescent substance in drip water in Heshangdong, then discussed the feasibility of using fluorescent substance as groundwater tracer. We came to the conclusion that fulvic acids in the cave drip water are dominant contributor to fluorescence, whose excitation wavelength is 304nm and emission wavelength is 407nm. In the annual cycle, the fluorescence intensity coincides with oxygen isotopic composition in seasonal variation （r = 0. 539,p〉0.99）. The peak values of δ^180 and the fluorescence intensity appear obviously after the winter recharge water arrives the cave, so this time difference can indicate the residence time of the cave drip water. Therefore, natural fluorescent substance can be used in tracing the process of unknown groundwater.