The stable isotopes of atmospheric precipitation that affect the isotopes of speleothem and cave water are controlled by a variety of factors, such as temperature, rainfall amount, altitude, vapor source and others. Knowledge in the factors causing rainfall stable isotopes change is one of the keys to understanding the cave water stable isotopes change of monsoon-sensitive area in the north-south China intersection. The samples collected from 4 ground water sites in Jiguan Cave and the instantaneous heavy rain during Aug.4th-6th, 2015 were analyzed, and combined with the precipitation oxygen and hydrogen isotopes data for samples from almost 6 years (2009-2015) collected in Jiguan Cave of Luanchuan County in Henan Province, leading to the following findings:① The precipitation was divided into 2 stages with different vapor sources (high-altitude water vapor from the South China Sea and inland areas from near the ground to evaporate moisture) that could be recorded in the δ18O of single rainfall by HYSPLIT model. ② The evaporation of stage 2 masked the temperature effect to some extent, which also decreased the slope and intercept of LMWL and d-excess of precipitation. ③ The δ18O values feature of cave drip water in Jiguan Cave during this rainfall was mainly a response to the summer monsoon precipitation from sea source vapor. The cave drip water of Jiguan Cave responded to the heavy rain very quickly, and the time was ~3 h. The δ18O of drip became heavier when dripping rate increased and then decreased slowly. The same pattern could be found in underground river with slight delay, and the pool near the cave entrance reflected the difference of precipitation δ18O in two stages.
Keywords: Jiguan Cave of Henan Province; cave water; evaporation; precipitation; vapor source; δ18O; δD.