Hydrochemical characteristics of ground ice in permafrost regions of the Qinghai-Tibet Plateau

Weihua Wang; Tonghua Wu; Lin Zhao; Ren Li; Changwei Xie; Yongping Qiao; Huiwen Zhang; Xiaofan Zhu; Shuhua Yang; Yanhui Qin; Junming Hao

doi:10.1016/j.scitotenv.2018.01.097

Hydrochemical characteristics of ground ice in permafrost regions of the Qinghai-Tibet Plateau

Sci Total Environ. 2018 Jun 1:626:366-376. doi: 10.1016/j.scitotenv.2018.01.097. Epub 2018 Feb 19.

Authors

Weihua Wang¹, Tonghua Wu², Lin Zhao³, Ren Li³, Changwei Xie³, Yongping Qiao³, Huiwen Zhang⁴, Xiaofan Zhu⁵, Shuhua Yang⁵, Yanhui Qin⁵, Junming Hao⁵

Affiliations

¹ Cryosphere Research Station on the Qinghai-Tibetan Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; College of Earth Environmental Sciences, Lanzhou University, Lanzhou 730000, China.
² Cryosphere Research Station on the Qinghai-Tibetan Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China. Electronic address: thuawu@lzb.ac.cn.
³ Cryosphere Research Station on the Qinghai-Tibetan Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
⁴ State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730070, China.
⁵ Cryosphere Research Station on the Qinghai-Tibetan Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 29353782
DOI: 10.1016/j.scitotenv.2018.01.097

Abstract

Ground ice is a distinctive feature of permafrost terrain. The vertical distribution and factors controlling the hydrochemistry of ground ice are important for studying soil moisture and salt migration during the freeze-thaw process in soil. These factors are also important components of hydrological cycles in cold regions. The hydrochemical characteristics of ground ice on the Qinghai-Tibetan Plateau (QTP) are not well known. We examined the characteristics of ground ice hydrochemistry using data from 9 soil profiles in permafrost regions of the central QTP. The isotopes and anion concentrations of subsurface water on the QTP were higher than those in Arctic polygonal ground regions. The spatial distribution of anions was complex. Well-developed hydrochemical depth gradients occurred within the soil profile. Isotopes decreased and anions increased with depth, suggesting general vertical patterns of soil hydrochemistry across different permafrost regions. Cl^- and SO₄^2- concentrations in soil water increased with depth, while NO₃^- concentration did not change with depth. Freeze-out fractionation, self-purification, and desalination greatly impact soil hydrochemistry. The major factors controlling variation of soil water chemistry were soil moisture, air temperature, and active layer thickness. The results could provide a framework for understanding ground ice origins and the moisture and salt migration pathways in the context of permafrost changes. This information could be useful in developing process-based permafrost hydrologic models.

Keywords: Ground ice; Hydrochemistry; Permafrost; Spatial distribution; Tibetan Plateau.