Hao Qichen, Xiao Yong, Liu Kui, Yang Hongjie, Chen Huizhu, Wang Liwei, Wang Jie, Zhang Yuqing, Hu Wenxu, Liu Yu, Li Binjie
Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes, Xiamen, 361021, China.
Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Science, Shijiazhuang, 050061, China.
Sci Rep. 2025 Mar 4;15(1):7643. doi: 10.1038/s41598-025-91659-9.
Groundwater is crucial for human society's development in piedmont plains, yet its hydrogeochemistry often exhibits complex spatial distributions due to the interplay of nature and human factors. Ninety-two phreatic groundwater samples were collected from a typical piedmont plain in northern China and analyzed using self-organizing map combined with hydrogeochemical simulation, diagrams, and the entropy-weighted water quality index. Groundwater samples were categorized into four clusters, demonstrating a gradual hydrogeochemical facies evolution from HCO-Ca to Cl-Mg·Ca and Cl-Na, along with an increase in NO content in the order of clusters IV, II, III, and I. Natural processes, including silicates weathering and reverse cation-exchange, establish the natural fundamental framework of groundwater chemistry, which is furtherly sculptured by agricultural substances input. Groundwater quality was predominantly excellent or good, with entropy-weighted water quality index (EWQI) values below 100 at over 92% of the sampling sites. Groundwater quality is relatively poorer in the upstream areas near the mountains and along the Hutuo River, where the stratum permeability is high, but improves in the downstream areas where permeability is lower. Agricultural land use and spatial variation in aquifer permeability are responsible for the observed spatial variations in groundwater chemistry. Agricultural contaminants warrant attention for the protection of groundwater quality in piedmont plains that with long-term agricultural activities, especially in the upstream areas near the mountains. This research improves the understanding of the spatial distribution and variation of groundwater chemistry in piedmont plains, and provides scientific guidance for related groundwater development and management.
地下水对山前平原地区人类社会的发展至关重要，然而由于自然因素和人为因素的相互作用，其水文地球化学特征往往呈现出复杂的空间分布。在中国北方一个典型的山前平原采集了92个潜水地下水样本，并采用自组织映射结合水文地球化学模拟、图表以及熵权水质指数进行分析。地下水样本被分为四类，显示出从HCO-Ca到Cl-Mg·Ca和Cl-Na的逐渐演化的水文地球化学相，同时NO含量按IV、II、III和I类的顺序增加。包括硅酸盐风化和阳离子交换逆向反应在内的自然过程奠定了地下水化学的自然基本框架，而农业物质的输入则进一步塑造了这一框架。地下水水质总体优良，超过92%的采样点的熵权水质指数（EWQI）值低于100。在靠近山区的上游地区和沿滹沱河一带，地层渗透率高，地下水水质相对较差，但在渗透率较低的下游地区水质有所改善。农业土地利用和含水层渗透率的空间变化是观测到的地下水化学空间变化的原因。在长期进行农业活动的山前平原地区，特别是在靠近山区的上游地区，农业污染物对地下水水质保护值得关注。本研究增进了对山前平原地下水化学空间分布和变化的理解，并为相关的地下水开发和管理提供了科学指导。
