Arid Zone Research ›› 2025, Vol. 42 ›› Issue (2): 258-273.doi: 10.13866/j.azr.2025.02.07

• Land and Water Resources • Previous Articles     Next Articles

Hydrochemical characteristics and enrichment mechanisms of high-arsenic groundwater in the Aksu River Basin, Xinjiang

LU Li1,2,3(), GE Yanyan3(), LI Sheng3, ZHANG Yun3,4   

  1. 1. College of New Energy and Environment, Jilin University, Changchun 130000, Jilin, China
    2. Institute of Water Resources and Environment, Jilin University, Changchun 130000, Jilin, China
    3. College of Geology and Mining Engineering, Xinjiang University, Urumqi 830046, Xinjiang, China
    4. Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China
  • Received:2024-07-14 Revised:2024-11-13 Online:2025-02-15 Published:2025-02-21
  • Contact: GE Yanyan E-mail:luli0401@sina.com;gyyxjdxgbc@163.com

Abstract:

In the Aksu River Basin, 20% of the domestic and irrigation water comes from groundwater, making it crucial to understand the distribution and formation of high-arsenic (As) groundwater in the area. Based on the hydrochemical and isotope results, graphical methods were used to analyze the hydrochemical characteristics of the groundwater and the spatial distribution and forms of arsenic, revealing the As occurrence environment combined with geological, geomorphological, and hydrogeochemical processes. The results revealed that the single-structure phreatic water is alkaline oxidizing brackish water, the phreatic water in the confined water area is alkaline weakly oxidizing saline water, and the confined water is alkaline reducing fresh water. The As content ranged from 0.05 to 160 µg·L-1, with a rate exceeding the standard of 19.5%. The hydrochemical types of high-As groundwater are mainly Cl·SO4-Na, SO4·Cl-Na·Ca, and Cl-Na, distributed in confined and phreatic water in the area downstream of the Aksu and Tailan Rivers at a depth of 10-42 m. From the mountainfront to the fine soil plain, the occurrence environment changes from weakly oxidizing to reducing. The As content and saturation index of the groundwater generally exhibited an increasing trend. The single-structure phreatic water and confined water were mainly controlled by the water-rock interaction. In contrast, the phreatic water in the confined water areas was mainly controlled by the evaporation concentration. The distribution of groundwater As is mainly related to structural factors, with realgar dissolution being the primary natural source. The arid climate and the geological, geomorphological, and hydrogeological conditions create external conditions for the enrichment of high-As groundwater. Factors like pH, desulfurization process, Eh, and groundwater circulation patterns affect As release. This study helps us understand the formation and evolution of high-As groundwater in the Aksu River Basin, which is crucial for ensuring water supply safety.

Key words: Aksu Rive Basin, high-arsenic groundwater, arid region, genesis analysis, occurrence environment