Hydrochemical characteristics and quality evaluation of groundwater in terms of health risks in Luohe aquifer in Wuqi County of the Chinese Loess Plateau, northwest China

Abstract

Groundwater is the main source of water for domestic and agricultural purposes in Wuqi County on the Loess Plateau. The present study was carried out to assess the hydrochemical characteristics and quality of groundwater in the Luohe aquifer, which is a crucial aquifer for water supply. For this study, 22 groundwater samples and 6 surface water samples were collected for analysis. Hydrochemistry and hydrochemical facies of groundwater were analyzed using statistical analysis and Tri-linear diagram. Gibbs diagram, correlation analysis and bivariate plots were used to investigate the natural evolution mechanisms of groundwater and surface water. Potential health risks of nitrate and Cr⁶⁺ through drinking water ingestion for adults and children were estimated. The results show that the major hydrochemical facies is Cl·SO₄-Na, mixed Cl·SO₄·HCO₃-Na and SO₄·Cl-Mg·Na types, and high concentration of Na⁺ is a remarkable feature of groundwater in the study area. Groundwater chemistry evolution is affected by rock weathering and evaporation. The high concentrations of Na⁺, SO₄^2- and TDS suggest that groundwater is not suitable for irrigation purposes. According to WQI values, above 80% of the groundwater samples are fair quality water. It is also found that the groundwater of the study area is contaminated with nitrate and Cr⁶⁺. Children are at higher health risk than adults. Multiple measures such as establishing new centralized water supply sources and inter-basin water transfer projects have also been proposed in this study to guarantee the safety of sustainable groundwater supply.

Keywords:

• Groundwater quality
• nitrate
• heavy metal
• health risk
• Loess Plateau

Acknowledgment

We are also very grateful to the anonymous reviewers and the editor for their useful and constructive comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support has been received from various agencies for the research presented in this article: the National Natural Science Foundation of China (41502234, 41602238, 41572236 and 41761144059), the Research Funds for Young Stars in Science and Technology of Shaanxi Province (2016KJXX-29), the Special Funds for Basic Scientific Research of Central Colleges (300102298301), the Fok Ying Tong Education Foundation (161098), the General Financial Grant from the China Postdoctoral Science Foundation (2016M590911), the Special Financial Grant from the China Postdoctoral Science Foundation (2017T100719), the Special Financial Grant from the Shaanxi Postdoctoral Science Foundation (2016BSHTDZZ03), and the Ten Thousand Talents Program.