Analysis of Groundwater Chemical Characteristics and Boron Sources in the Oasis Area of the Cherchen River Basin in Xinjiang, China

The oasis area of the Cherchen River Basin (OACRB) is located in the southeast edge of the Tarim Basin in Xinjiang, China. High boron (B) groundwater is observed in the OACRB according to 40 groundwater samples collected in May 2023. Identification of the chemical characteristics and B sources of groundwater in the OACRB is of great significance for the sustainable development and utilization of groundwater resources and the protection of animals, plants and human health. To explore the chemical characteristics and main B sources of groundwater, Piper three-line diagram, Gibbs diagram, correlation analysis, hydrogeochemical simulation and absolute principal component analysis (PCA-APCS-MLR) were used for analysis. The contribution of different factors to groundwater B was quantitatively evaluated. The results showed that the groundwater is weakly alkaline (with an average pH of 7.94) and mainly brackish water and saline water with Cl− and Na+ as the main anions and cations. The groundwater is dominated by SO4 · Cl-Na type. The average concentration (ρ) of groundwater B in the study area was 1.48 mg·L−1 with the over-standard rate was 45.0%. The APCS-MLR receptor model analysis revealed that groundwater chemical components including B were mainly derived from leaching-enrichment, human activity, primary geological factors, and unknown sources. Groundwater B is obviously greater than the standard limit, which is mainly due to agricultural activities (fertilizers and pesticides) and unknown sources.