Determination and Source Analysis of Hydrochemical Components in Different Water Bodies during the Normal Water Period in the Nandagang Wetland of Hebei Province, China

In recent years, the Nandagang wetland in Hebei Province has been facing a multidimensional water environmental crisis characterized by decreasing water volume, deteriorating water quality, and declining ecological service functions. Analyzing the sources and causes of major ions is crucial for improving the wetland's aquatic ecological environment. Samples of river water, lake water, seawater, and groundwater in the Nandagang wetland, Cangzhou City, Hebei Province, were analyzed. Comprehensive methods, including mathematical statistics, correlation analysis, ion ratios, and the positive matrix factorization (PMF) model, were employed to analyze the hydrochemical characteristics and formation mechanisms of different water bodies. The results indicate: (1) River water, lake water, groundwater, and seawater in the study area are all weakly alkaline Cl-Na type water. (2) The water bodies in the study area are strongly controlled by evaporation and concentration. From inland to coastal areas, the total dissolved solids (TDS) content in river water and groundwater gradually increases, and evaporation intensifies. (3) From the recharge area to the discharge area, the HCO₃⁻/Cl⁻ ratio in groundwater gradually decreases. The main ions in shallow groundwater originate from seawater. Evaporation exacerbates groundwater salinization, while cation exchange is a secondary factor. The weakly alkaline hydrochemical environment facilitates ion enrichment. Human activities such as agricultural fertilization in the groundwater recharge area and livestock farming in the groundwater stagnant zone are anthropogenic factors influencing groundwater chemical composition. The main ions in the study area’ lake water originate from the northern salt fields, with ecological water replenishment being the secondary source. Petrochemical plants are a potential factor affecting the lake water’s chemical composition. The exceedance rates of NO₃⁻ concentration standards for river water, lake water, and groundwater samples in the study area were 37.5%, 8.3%, and 37.5%, respectively. Key factors causing groundwater exceedance include agricultural fertilization, animal manure, and seawater mixing. It is recommended to control human activities such as agricultural fertilization and aquaculture to reduce the nitrate load in the regional water bodies. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202408200173.