Hydrochemical characteristics and pollution sources of groundwater in the Zhuxihe River Basin, Hainan Province, China

Groundwater quality in the Zhuxihe River Basin, Hainan Province, is increasingly threatened by both natural and anthropogenic factors. This study aims to evaluate groundwater quality using a hierarchical ladder evaluation (HLE) method, integrated with single factor evaluation (SFE) and fuzzy comprehensive evaluation (FCE) methods. A total of 74 groundwater samples were collected from the Zhuxihe River Basin, covering 41 chemical indicators. Results show that while 70% of the samples are classified as Grades I–III (suitable for drinking after treatment), 30% fall into Grades VI–V (severely contaminated), particularly in coastal and river terrace areas. The primary contributors to groundwater degradation include saltwater intrusion, agricultural and aquaculture runoff, and the geogenic release of heavy metals. The final results indicate that the integrated HLE-SFE-FCE method proves to be an effective tool for assessing groundwater quality. This study provides first-hand data for local groundwater pollution prevention and control efforts, emphasizing the need for targeted management strategies to mitigate pollution and ensure the long-term sustainability of groundwater resources.