[Major Ionic Features and Their Possible Controls in the Water of the Niyang River Basin]

In order to study the hydrochemical characteristics and their possible controls for the chemical composition of the water from the Niyang River Basin, 30 samples were collected from wells, springs, and the river in 2014 and major ion concentrations were measured. Descriptive statistics, the Gibbs figure, an ion ratio, and Piper triangular diagrams were used to investigate the hydrochemical characteristics, influencing factors, and hydrochemical evolution of the water in the basin. The results showed that the major cations in this water were Ca²⁺ and Mg²⁺, accounting for more than 84% of cations and the main anions were HCO₃^- and SO₄^2-, accounting for more than 97% of anions The hydrochemical typology of the water is HCO₃·SO₄(SO₄·HCO₃)-Ca·Mg (Mg·Ca). The total dissolved solids (TDS) in the water ranges from 79.11 to 290.48 mg·L^-1 with an average of 165.21 mg·L^-1. The chemical composition of water samples is located to the left of the Gibbs model, which indicates that the chemical process of Niyang River Basin are controlled by rock weathering. According to the principal component analysis and correlation analysis, the hydrochemical composition is controlled by silicate weathering, however, carbonate weathering also plays an important role.