Ground ice at depths in the Tianshuihai Lake basin on the western Qinghai-Tibet Plateau: An indication of permafrost evolution

Yuzhong Yang; Qingbai Wu; Guanli Jiang; Peng Zhang

doi:10.1016/j.scitotenv.2020.138966

Ground ice at depths in the Tianshuihai Lake basin on the western Qinghai-Tibet Plateau: An indication of permafrost evolution

Sci Total Environ. 2020 Aug 10:729:138966. doi: 10.1016/j.scitotenv.2020.138966. Epub 2020 Apr 24.

Authors

Yuzhong Yang¹, Qingbai Wu², Guanli Jiang³, Peng Zhang³

Affiliations

¹ State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China. Electronic address: yangyuzhong08@lzb.ac.cn.
² State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China. Electronic address: qbwu@lzb.ac.cn.
³ State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.

PMID: 32361452
DOI: 10.1016/j.scitotenv.2020.138966

Abstract

The stable-isotope data of ground ice from a deep borehole (~46 m) at the Tianshuihai (TSH) lake basin on the northwestern Qinghai-Tibet Plateau (QTP) are presented together with cryolithological information. Remarkable variations in the stable isotope composition of ground ice at depths allow a division of five clearly delineated stages. The remarkable deviations in stable isotopes of ground ice during each stage underline different initial source water and formation processes, indicating considerable fluctuations in paleo-lake conditions and multiple patterns of climatic-induced permafrost evolutions. In combination with the ground ice isotopes for two deep boreholes on the interior QTP, the position of the present permafrost table is found at 2-3 m. Two possible positions of paleo-permafrost tables at depths of 7-8 and 15-16 m are identified based on the ice isotopic composition of wellbores in combination with those from the other two deep boreholes on the interior QTP. The high uniformity in stable isotopic composition of ground ice below the depth of 16 m may have reflected the consistent regional climate transitions and the resultant permafrost evolution on the QTP. This study provides some new insights on the ground ice as an indicator for permafrost evolution on the QTP.

Keywords: Ground ice; Permafrost evolution; Permafrost table; Qinghai-Tibet Plateau; Stable isotopes.