Jung Hyejung, Jeen Sung-Wook, Lee Hyoungseok, Lee Jeonghoon
Department of Science Education, Ewha Womans University, Seoul 03760, Republic of Korea.
Department of Earth and Environmental Sciences, Jeonbuk National University, Jeonju 54907, Republic of Korea; Department of Environment and Energy, Jeonbuk National University, Jeonju 54907, Republic of Korea.
Sci Total Environ. 2022 Jun 15;825:153784. doi: 10.1016/j.scitotenv.2022.153784. Epub 2022 Feb 16.
Antarctica is highly susceptible to climate and environmental change. In particular, climate change can lead to the warming of permafrost and the development of active layers in permafrost areas, resulting in variations in hydrological characteristics. This study investigated the hydrological process associated with a stream in a snow-dominated headwater catchment on King George Island, maritime Antarctica, during austral summer using the chemical and isotopic compositions. During the cold period, as the snowmelt rate decreased, the amount of new water also decreased. Hence, the electrical conductivity (EC) increased because the contribution of supra-permafrost groundwater ("old" water), which occurs in the active layer, increased more during the cold period than during the warm period. Moreover, diel variations in the stable isotopic compositions (δO and δD) of snowmelt ("new" water) were clearly observed in the stream water, indicating that runoff was the dominant flow path of snowmelt during the cold period. In contrast, during the warm period, the amount of snowmelt increased and the EC value decreased as a result of the dilution effect. In addition, compared with the cold period, diel variations in the isotopic compositions of the stream water were attenuated during the warm period. This attenuation effect was not due to the increased contribution of old water; instead, it was due to the contribution of new water with a low-amplitude signal in the diel variations of the isotopic compositions. Thus, the observed diel variations in the isotopic compositions of the stream water during cold and warm periods suggest that this catchment is dominated by new water. These findings are helpful for improving our understanding of climate-related changes in the hydrological pathways and water-related ecosystems of polar catchments.
南极洲极易受到气候和环境变化的影响。特别是，气候变化会导致多年冻土变暖以及多年冻土区活动层的发育，从而导致水文特征发生变化。本研究利用化学和同位素组成，对南极海洋性乔治王岛一个以降雪为主的源头集水区内一条溪流的水文过程进行了调查，调查时间为南半球夏季。在寒冷时期，随着融雪速率降低，新水量也减少。因此，电导率（EC）增加，因为活动层中出现的永冻层上地下水（“老”水）的贡献在寒冷时期比温暖时期增加得更多。此外，在溪流水体中清晰观察到融雪（“新”水）的稳定同位素组成（δO和δD）的日变化，这表明在寒冷时期径流是融雪的主要流动路径。相反，在温暖时期，融雪量增加，由于稀释作用，EC值降低。此外，与寒冷时期相比，温暖时期溪流水体同位素组成的日变化减弱。这种减弱效应并非由于老水贡献增加；相反，是由于同位素组成日变化中低振幅信号的新水的贡献。因此，在寒冷和温暖时期观察到的溪流水体同位素组成的日变化表明，该集水区以新水为主。这些发现有助于增进我们对极地集水区水文路径和与水相关生态系统中与气候相关变化的理解。
