Evaluation of thermokarst lake water balance in the Qinghai–Tibet Plateau via isotope tracers

• Published in: The Science of the total environment 2018-09, Vol.636, p.1-11
• Main Authors: Gao, Zeyong, Niu, Fujun, Lin, Zhanju, Luo, Jing, Yin, Guoan, Wang, Yibo
• Format: Article
• Language: English
• Subjects: Evaporation; Qinghai–Tibet plateau; Thermokarst lake; Water balance
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.04.103

Thermokarst lakes are a ubiquitous landscape feature, which widely distributed in the pan-arctic and some low latitude regions, and are associated with regional hydrological processes. The studies were taken to obtain a better understanding of the water balance of thermokarst lakes in the Qinghai–Tibet Plateau (QTP) in order to gain insight of the regional hydrological cycle. The characteristics of the stable isotopes δ 18O and δ D were investigated in precipitation, permafrost meltwater, and thermokarst lake water in the continuous permafrost region of the QTP and analyzed the lake water balance using the isotope mass model. The results showed that the δ D–δ 18O relationship in the thermokarst lakes (δ D = 5.45 δ 18O − 18.95) differed from that of the local precipitation (δ D = 8.30 δ 18O + 18.49) and permafrost meltwater (δ D = 5.78 δ 18O − 23.41), and the mean isotope compositions in the thermokarst lakes were −7.2‰ in δ 18O and −58.0‰ in δ D. The more positive isotope signals in thermokarst lakes than in the precipitation and permafrost meltwater revealed that the lakes had experienced stronger isotope enrichment. Additionally, the evaporation-to-inflow ratio (E/I) values were