Arid Zone Research ›› 2025, Vol. 42 ›› Issue (5): 800-809.doi: 10.13866/j.azr.2025.05.03

• Land and Water Resources • Previous Articles     Next Articles

Chemical characteristics of groundwater and carbon cycle in desert areas: A case study of the eastern region of Ulan Buh Desert

JI Yaxin1,2(), LI Lu1,2, YANG Xuedong1,2, HOU Fulai1,2, ZHANG Meng1,2, DONG Shaogang1,2()   

  1. 1. School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, Inner Mongolia, China
    2. Key Laboratory of River and Lake Ecology of Inner Mongolia Autonomous Region, Inner Mongolia University, Hohhot 010021, Inner Mongolia, China
  • Received:2024-11-22 Revised:2025-02-05 Online:2025-05-15 Published:2025-10-22
  • Contact: DONG Shaogang E-mail:jiyaxin0217@163.com;groundwater@163.com

Abstract:

The desert groundwater exhibits a substantial storage capacity and a high concentration of dissolved inorganic carbon (DIC). Understanding the mechanisms governing carbon migration and transformation in desert groundwater is crucial for gaining deeper insights into the global carbon cycle. Based on groundwater flow system theory, this study collected 50 groundwater samples from the eastern part of the Ulan Buh Desert, Inner Mongolia, China. A combination of statistical analysis, Piper three-line diagram, Gibbs diagram, and hydrogeochemical modeling was employed to investigate the hydrochemical characteristics of groundwater in the study area and the mechanisms of carbon migration and transformation during groundwater flow. The results indicate that the groundwater in the study area is generally weakly alkaline. Unconfined water is classified as brackish, whereas confined water ranges from fresh to brackish. The dominant hydrochemical types are Cl-Ca∙Mg and Cl-Na. The groundwater chemistry is primarily influenced by evaporation concentration and water-rock interactions. The total carbon sequestration flux of phreatic water in the eastern Ulan Buh Desert ranges from 4.26-5.39 g·m-2·a-1. Among this, carbon uptake via water-rock interactions accounts for 1.14 g·m-2·a-1, while carbon input from precipitation recharge through the vadose zone contributes 3.12-4.25 g·m-2·a-1. These findings suggest that groundwater in the eastern Ulan Buh Desert exhibits a significant “carbon sink” effect, providing empirical evidence for the role of desert groundwater in the global carbon cycle.

Key words: groundwater, carbon cycle, hydrochemical characteristics, water-rock interaction