[Hydrochemical Characteristics, Controlling Factors and Water Quality Evaluation of Shallow Groundwater in Tan-Lu Fault Zone （Anhui Section）].

To study the hydrochemical characteristics, controlling factors, and groundwater quality of the Tan-Lu fault zone (Anhui section), 86 groundwater samples were taken from the areas surrounding the Tan-Lu fault zone (Anhui section), which included the Jianghuai Wavy Plain, the Yanjiang Hill Plain, and the Dabie Mountains in western Anhui. Descriptive statistics, Piper diagram, Gibbs diagram, ion ratio analysis, saturation index, chloride-alkalinity index, and entropy weight water quality index (EWQI) were used to comprehensively study the hydrochemical characteristics and controlling factors of groundwater and to evaluate its quality. The results showed that the shallow groundwater in the Tan-Lu fault zone (Anhui section) was weakly alkaline, with dominant anions and cations of HCO3-, Ca2+ and Na+, respectively, and the hydrochemical types were mainly HCO3-Ca·Mg and HCO3-Na·Ca. The solute source of groundwater was mainly controlled by water-rock interactions, and the weathering of silicate and carbonate rocks jointly contributed to the formation of the chemical components of groundwater. Strong cation exchange adsorption was an important factor causing Na+ enrichment. The overall quality of groundwater in the study area was good but was polluted to a certain extent by human activities. Most of the groundwater in the Jianghuai Wavy Plain and Yanjiang Hill Plain was not suitable for direct drinking. The results of this research have important implications for the sustainable development and utilization of shallow groundwater resources and environmental protection in the Tan-Lu fault zone (Anhui section).

[Hydrochemical Characteristics and Control Factors of Surface Water and Groundwater in Huainan Coal Mine Area].

To clarify the hydrochemical characteristics and control factors of surface and underground water in Huainan mining area, 115 groups of groundwater and 30 groups of surface water samples were collected, and the hydrogeochemical characteristics of surface water and groundwater in Huainan mining area were analyzed. Additionally, the hydrochemistry evolution law was discussed by comprehensively using mathematical statistics, the Piper triangular diagram, Gibbs diagram, mineral stability field diagram, and ion ratio relationship, etc. The results showed that the groundwater and surface water in the study area were weakly alkaline, the dominant anion was HCO3-, and the dominant cations were Ca+ and Na+. The hydrochemical types of groundwater and surface water were dominated by HCO3-Ca type and HCO3-Ca·Na·Mg type, respectively. The hydrochemical composition of groundwater and surface water was mainly controlled by rock weathering, as well as by alternating adsorption of cations and evaporation concentration. Silicate and carbonate minerals were mainly dissolved in the water-rock interaction. The main ions such as Ca2+, Mg2+, and HCO3- came from the dissolution of carbonate rocks. The Cl-, SO42-, NO3-, and Ca2+ were affected by exogenous inputs caused by human activities. The chemical components of groundwater and surface water in Huainan coal mining area were affected by water-rock interactions and human activities, and groundwater was greatly affected by human activities.