Hydrochemical environment in a typical conservation area in the Beijing-Tianjin-Hebei region: A case study in Xinglong County of Chengde

Characteristics of water environment and quality are the main controlling factors of water conservation and are of important significance in the rational utilization of regional water resources and ecologically sustainable development. To promote the overall utilization and protection of water resources in the Chengde are and its downstream area, the Xinglong county, a major source of water resources in the south of Chengde, is selected as a typical research area in this paper. Statistical analysis and GIS spatial analysis were used to adopt the 79 water samples collected in 2019, and hydrogeochemical graphic method was employed to comprehensively understand the spatial distribution characteristics of water chemistry, the provenance basis of major components, and the formation conditions and water conservation conditions. The research results indicate that the hydrochemical type in the study area is mainly of HCO₃-Ca·Mg type (62%) and is controlled by the widespread distribution of dolomite carbonate. The groundwater is generally in an oxidizing environment with good connectivity to the atmosphere, and hydrochemical compositions mainly come from the water-rock interactions in the process of leaching of atmospheric precipitation. The regional water quality conservation conditions are generally excellent. However, there are 3 groups of samples (SO₄^2- concentrations higher than the national standard, accounting for 3.80%) and 2 groups of samples (NO₃^- concentrations higher than the national standard, accounting for 2.53%) in the main ionic components, which are related to local mining activities and human activities and should be paid attention to. The TDS in the water in the area is low, and the beneficial elements such as Sr and Se are rich in the distribution areas of metamorphic rocks and intrusive rocks, forming advantageous conditions for water conservation in the Beijing-Tianjin-Hebei region.