Obtaining a better understanding of groundwater dynamics in permafrost zones is a critical issue in permafrost hydrology. This includes assessing the impacts of climate change on permafrost thaw and ground ice-melt. Both permafrost thaw and ground ice-melt can be related to groundwater discharges (i.e. spring discharges), and spring water is an important local water resource; accordingly, changes in these processes can have large impacts on local people and their subsistence activities. To detect permafrost thaw and ground ice-melt in the permafrost zone of Mongolia, groundwater ages of several spring discharges were determined using two transient tracers: tritium (³H) and chlorofluorocarbons (CFCs). Spring water samples were collected seasonally from 2015 to 2019 at seven spring sites around the Khangai Mountains in central Mongolia. The sites included two thermokarst landscapes on the northern and southern sides of the mountains. The ³H and CFC concentrations in the spring water in the thermokarst landscapes were very low, especially on the southern side of the mountains, and the estimated mean groundwater age for these sites was older than that for the other sampled springs. Consequently, the young water ratios of the thermokarst sites were lower than those for the other springs. This ratio, however, showed a gradual increase with time, which indicates that recently recharged rainwater began to contribute to the spring discharge at the thermokarst sites. An atmospheric water budget analysis indicated that net recharge from modern and recent precipitation to shallow groundwater in the summer season was almost zero on the southern side of the mountains. Thus, we inferred that the spring water at the thermokarst sites on the southern side of the mountains contained large amounts of ground ice-melt water.

更好地了解多年冻土带中的地下水动力学是多年冻土水文学中的关键问题。这包括评估气候变化对多年冻土融化和地面冰融化的影响。多年冻土融化和地面冰融都可能与地下水排放（即泉水排放）有关，泉水是当地重要的水资源。因此，这些过程的变化会对当地人民及其生存活动产生重大影响。为了检测蒙古多年冻土区的多年冻土融化和地面融冰情况，使用两个瞬态示踪剂确定了几种春季排泄物的地下水年龄：tri（³H）和氯氟烃（CFC）。从2015年到2019年，从蒙古中部Khangai山周围的七个春季场采集了春季水样。这些地点包括山脉北部和南部的两个热喀斯特景观。在³喀斯特地貌景观中泉水中的H和CFC浓度非常低，特别是在山脉的南侧，这些地点的平均地下水年龄估计比其他采样泉年龄大。因此，地热岩溶区的幼水率低于其他泉水。但是，该比例随时间逐渐增加，这表明最近补给的雨水开始对热岩溶区的春季排放起了作用。一项大气水预算分析表明，在夏季，山脉南部南部从现代和近期降水向浅层地下水的净补给几乎为零。因此，