Arid Zone Research ›› 2021, Vol. 38 ›› Issue (1): 68-75.doi: 10.13866/j.azr.2021.01.08

• Water Resources and Utilization • Previous Articles     Next Articles

Hydrochemical characteristics and cause analysis of the shallow groundwater in Shihezi City

ZENG Xiaoxian1,2(),ZENG Yanyan1,2(),ZHOU Jinlong1,2,LEI Mi1,2,SUN Ying1,2   

  1. 1. College of Water Conservancy and Civil Engineering, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
    2. Xinjiang Hydrology and Water Resources Engineering Research Center, Urumqi 830052, Xinjiang, China
  • Received:2020-03-25 Revised:2020-06-08 Online:2021-01-15 Published:2021-03-05
  • Contact: Yanyan ZENG E-mail:1910169441@qq.com;644257818@qq.com

Abstract:

We studied the groundwater hydrochemical characteristics from the Shihezi City, Xinjiang. We used descriptive statistics and trilinear diagrams of Piper to analyze the main groundwater chemical contents and hydrochemical types of 19 phreatic groundwater and 25 shallows confined to groundwater samples. We used Schoeller diagram, Gibbs diagram and ion ratio diagram to analyze the causes of groundwater chemical characteristics formation. The shallow groundwater had weak alkaline water with low salinity, and the total groundwater hardness was 68.4%. The groundwater total dissolved solids were 97.7% in fresh groundwater. The main cations were Ca2+ and Na++K+, and the main anions were HCO3- and SO42-. The groundwater recharge sources were different in space, and ions might migrate from relatively high concentration points to relatively low concentration points along the groundwater flow direction. The primary groundwater hydrochemical types were HCO3-Ca and HCO3·SO4-Ca, followed by HCO3·SO4-Na. The Gibbs diagram results showed that the phreatic groundwater was mainly affected by both rock weathering and infiltration recharge after evaporation-concentration of surface water, while shallow confined groundwater was affected primarily by rock weathering. The saturation index method and ion ratio diagram indicated that the main ions in groundwater originated from the dissolution of evaporite. The dissolution of halite was the primary source of K+ and Na+ in groundwater, and the dissolution of evaporite or calcium magnesium silicate was the main source of Ca2+ and Mg2+. There was a negative correlation between γ(Na+-Cl-) and γ(Ca2++Mg2+)-γ(HCO3- + SO42-), indicated that cation exchange also played an essential role in the hydrochemical formation of shallow groundwater. Shihezi City is a typical oasis city in the Northwest arid region. Our results revealed the formation mechanism of shallow groundwater and provided a scientific basis for the rational development and utilization of shallow groundwater and water treatment.

Key words: shallow groundwater, hydrochemical characteristics, cause analysis, Shihezi City