Surface Water Quality Evaluation and Pollution Source Analysis at the Confluence of the Wei River and Yellow River, China

Abstract

Water quality is a critical aspect of environmental health, affecting ecosystems, human health, and economic activities. In recent years, increasing pollution from industrial, agricultural, and urban sources has raised concerns about the deterioration of water quality in surface water bodies. Therefore, this study investigated the spatio-temporal distribution of water elements, human health risks of surface water, and pollutant sources at the confluence of the Wei River and the Yellow River. Using 80 samples collected during both wet and dry seasons, the content of the 22 water chemistry indicators was tested. A statistical analysis, Piper diagram, and entropy water quality index were employed to analyze the chemistry indicator content, hydrochemical composition, and water environmental quality of the surface water in the area. Moreover, the health risk assessment model was utilized to evaluate the carcinogenic and non-carcinogenic health risks associated with heavy metal elements in surface water. Finally, correlation heatmaps and a principal component analysis were used to identify potential pollution sources in the study area. The results indicated that Cr(VI) and NH3-N were the main pollutants during the wet season, while surface water quality during the dry season was mainly influenced by F−. The hydrochemical type in the study area was mainly SO4Cl-CaMg. The health risk assessment revealed a high carcinogenic risk in the study area, with Cr(VI) being the primary heavy metal element contributing to health risks. The correlation and principal component analysis results show that the surface water environment in the study area was influenced by soil characteristics (soils containing F− in the Dalí region, soils containing heavy metals in the Tongguan region), native geological environment (mineral resources and terrain conditions), and industrial activities (ore smelting). This study identified the key pollution indicators, the priority control areas, and the extent of the human health impact of the surface water at the confluence of the Wei River and the Yellow River, guiding targeted management of surface water environments.