Water quality characteristics of surface and groundwater sources in Lower reaches of Yellow River, Northern China

Abstract Drinking water sources including reservoirs, rivers, springs and groundwater in lower reaches of Yellow River, have been seasonally investigated to assess the water quality characteristics of different types of water sources during 2019 and 2021, and to find their differences in water quality based on multivariate statistical analysis and hydrochemical types. The water quality varied greatly among different water bodies, and based on the water quality characteristics, the four types of water bodies were divided into surface (reservoirs and rivers) and groundwater (groundwater and springs). Five principal components were extracted by, together explaining 84% of all the variance information by log-transformed principal component analysis (PCA), which represented anions, formation potential of disinfection by-products precursors (DBPFP), nutrients and phytoplankton biomass effected the water quality of these waterbodies. The matter sources of surface water and groundwater were quite different, with dominant by organic compounds and inorganic matters in surface water and groundwater, respectively. However, the similar humus carbon-to-nitrogen ratio (HS-C/N) values indicated that the organic matter in groundwater is affected to a certain extent by the replenishing surface water. In the aspect of inorganic ions, these waterbodies were more affected by Na-Cl-SO4 in wet season, while Ca-HCO3-CO3 in dry season. Gibbs diagram suggested that anions and cations were mainly contributed by atmospheric precipitation for the surface water, while they were mainly derived from rock weathering for groundwater. It is hoped that this study will help to evaluate the pollution risk and the feasibility of long-term implementation of artificial source remediation projects.