“23·7”暴雨对永定河出山口地下水水质的影响机制  

The impact mechanism of the"23·7"heavy rainstorm on groundwater quality at the Yongding River Foothills

作　　者：马硕 何宝南 张学航 何江涛 龙翔云[1,2] 杨珊珊 史芫芫 MA Shuo;HE Bao-nan;ZHANG Xue-hang;HE Jiang-tao;LONG Xiang-yun;YANG Shan-shan;SHI Yuan-yuan(Key Laboratory of Groundwater Conservation of Ministry of Water Resources(in preparation),Beijing 100083,China;School of Water Resources and Environment,China University of Geosciences(Beijing),Beijing 100083,China;Beijing Municipal Research Institute of Eco-Environmental Protection,Beijing 100037,China)

机构地区：[1]水利部地下水保护重点实验室(筹),北京100083 [2]中国地质大学(北京)水资源与环境学院,北京100083 [3]北京市生态环境保护科学研究院,北京100037

出　　处：《中国环境科学》2025年第4期1973-1984,共12页China Environmental Science

基　　金：北京市地下水污染风险源分类分级管控项目(HCZB-2023-ZB0078)。

摘　　要：为探究“23·7”特大暴雨对门头沟平原区地下水水质的影响及机制,以永定河出山口为研究对象,通过对比暴雨前后地表及地下水水质变化,结合水文地球化学模拟及微生物表征技术进行成因分析.结果显示:暴雨洪水后地下水中Ca^(2+)和HCO_(3)^(-)浓度均值上升9.75%~14.68%,Cl^(-),SO_(4)^(2-),F^(-),总Fe,总Mn浓度均值下降26%~86.92%,与地表水变化趋势相同,表明地下水水化学变化主要由受影响的地表水入渗引起.然而,地下水中K^(+),溶解氧(DO),氧化还原电位(Eh),NO_(3)^(-)-N指标变化趋势与地表水相反,表明地下水水化学变化不仅仅是与地表水简单的物理混合.PHREEQC反向模拟结果表明,暴雨影响下地下水水化学演化受物理混合与稀释,矿物溶解沉淀,反硝化以及硫酸盐还原作用共同调节.具体而言,物理混合与稀释贡献为15.82%,在此基础上,硅酸盐矿物溶解增加Ca^(2+)浓度,硅酸盐和蒸发岩矿物溶解与阳离子交换作用共同维持了Na^(+)平衡,降雨入渗与有机质分解增加了HCO_(3)^(-)浓度,反硝化与硫酸盐还原作用使得NO_(3)^(-)和SO_(4)^(2-)浓度降低.值得关注的是,特大暴雨加剧了首钢工业园附近高浓度Fe污染的稀释扩散,尽管稀释作用使Fe的超标浓度峰值由89.5mg/L降低至25.4mg/L,但Fe超标的数量却由1个增加至4个,比例达66.67%.同时,这一过程显著促进了地下水中Fe(Ⅱ)自养反硝化菌属的富集,提高了反硝化速率,显著降低了地下水中NO_(3)^(-)-N的浓度.To investigate the impact and mechanisms of the"23·7"heavy rainstorm event on groundwater quality in the Mentougou Plain area,the area at the foothills of the Yongding River was selected as the study area.By comparing the alterations in groundwater and surface water quality before and after the rainstorm,and integrating hydrogeochemical modeling with microbial characterization,we analyze the underlying causes.The results showed that the average concentrations of Ca^(2+)and HCO_(3)^(-)in the groundwater increased by 9.75%to 14.68%,while those of Cl^(-),SO_(4)^(2-),F^(-),total Fe,and total Mn decreased by 26%to 86.92%after the rainstorm,consistent with the trend in surface water.It suggested that the variation in groundwater chemistry was primarily driven by the infiltration of affected surface water.However,the trends in K^(+),dissolved oxygen(DO),redox potential(Eh),and NO_(3)^(-)-N in groundwater are opposite to those in surface water,indicating that groundwater chemistry changes were not solely the result of simple physical mixing with surface water.The reverse simulation results using PHREEQC indicate that under the influence of the rainstorm,the evolution of groundwater chemistry is regulated by a combination of physical mixing and dilution,mineral dissolution and precipitation,denitrification,and sulfate reduction.Specifically,physical mixing and dilution account for 15.82%of the alterations.Based on it,the silicate minerals dissolution increases the Ca^(2+)concentration,while the dissolution of silicate and evaporite minerals,in combination with cation exchange,helps maintain Na^(+)balance.The infiltration of rainwater and the decomposition of organic matter increase the HCO_(3)^(-)concentration.The denitrification and sulfate reduction decrease NO_(3)^(-)and SO_(4)^(2-)concentrations.Notably,the heavy rainstorm exacerbated the dilution and diffusion of high-concentration Fe contamination around the Shougang Industrial Park.Although dilution reduced the peak concentration of Fe exceeding the standard from

关 键 词：永定河 “23·7”特大暴雨 地下水水质 反向模拟 微生物响应 

分 类 号：X523[环境科学与工程—环境工程]