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大气降水稳定同位素受温度、雨量、海拔高程、水汽源等多种因素控制,进而影响洞穴水及沉积物的同位素变化.为了更好地认识我国南北交汇带季风敏感区洞穴水对降水的响应过程,本研究分析了2015年8月4~6日河南栾川县鸡冠洞强降雨和洞内4处地下水点样品,并结合2009~2015年栾川地区近6年大气降水氧氘同位素数据研究发现:1采用HYSPLIT模型可以将鸡冠洞强降雨划分为不同水汽来源的2个阶段:高空来自南中国海的水汽以及近地面来自内陆局地蒸发的水汽,并且可以记录在单场降雨期间雨水的δ~(18)O变化特征上.2近地面来自内陆局地蒸发水汽的蒸发过程一定程度上掩盖了温度效应,并使局地大气降水线的斜率、截距和雨水过量氘均减小.3此次降雨期间鸡冠洞洞穴滴水δ~(18)O特征主要响应夏季风海源水汽的降水;鸡冠洞洞穴滴水对降雨响应最快,间隔时间约为3 h,滴水δ~(18)O随滴率升高变重,之后缓慢变轻;地下河具有相似的模式,稍有滞后;靠近洞口的池水反映出不同阶段的雨水δ~(18)O变化的差异.
Stable isotopes of precipitation in the atmosphere are controlled by many factors such as temperature, rainfall, elevation and water vapor source, which in turn affect the isotope variation of cave water and sediments.In order to better understand the response of cave water to precipitation in the monsoon sensitive area , The present study analyzed the strong rainfall of Jiguguan Cave in Luanchuan County, Henan Province from August 4 to August 6, and the samples of four groundwater points in the cave. Based on the data of oxygen and deuterium isotope data of atmospheric precipitation in Luanchuan from 2009 to 2015 : 1 The HYSPLIT model can be used to divide the heavy rainfall in Jiguan Cave into two stages with different sources of water vapor: the water vapor from the South China Sea at high altitude and the water vapor evaporated from the inland area near the surface, and the rainfall during the single rainfall period δ ~ (18) O .2 The evaporating process of evaporative water vapor from the inland area covered the temperature effect to some extent, and decreased the slope and intercept of local precipitation lines and excess deuterium .3 During the rainfall, the δ 18 O features of the cave in Jiguguan Cave mainly responded to the precipitation of water vapor from the source of the summer monsoon. The drip of water in the cave of Jiguguan Cave responded fastest to rainfall with an interval of about 3 h. The drip δ ~ (18) O becomes heavier as the drop rate increases, and then slowly lightens. The underground river has a similar pattern with a slight lag. The water near the hole mouth reflects the difference of δ 18 O in different stages of rainfall.