松嫩平原典型高氟区水库周边浅层地下水化学特征及高氟成因

Chemical characteristics and high-fluoride origins of shallow groundwater around typical high fluorine reservoir in Songnen Plain

高氟地下水极大地威胁水源安全,影响人体健康与生态环境.尽管近年来对高氟地下水开展了大量研究,但对水库周边浅层地下水中氟的地球化学背景、时空分布变化以及演变趋势仍缺乏系统认识.该研究综合运用数理统计、ArcGIS空间插值、Piper三线图、端元图、Gibbs图和MINTEQ地球化学模拟等方法,探讨吉林省向海水库浅层地下水中氟离子(F-)的时空分布特征及影响机制.结果表明:①向海水库周边浅层地下水中F-含量较高,浓度为0.20~5.18 mg·L^(-1),平均浓度为1.76 mg·L^(-1),高于我国《地下水质量标准》(GBT 14848—2017)中规定的1.00 mg·L^(-1)的浓度限值,属于高氟地下水,F-浓度呈西北区域最高、东南次之、东北和西南最低的空间分布趋势;②该区域浅层地下水的水化学类型复杂,水化学特征以HCO3-Na、HCO3-Na∙Ca和HCO3-Na∙Mg型为主;③F-浓度与区域水化学环境密切相关,蒸发浓缩、水岩相互和阳离子交换作用等理化过程共同引起的含氟矿物溶解导致了该区域地下水中F-的富集.该研究明晰了向海水库周边浅层地下水的空间分布特征,厘清了水库周边区域浅层地下水中高氟的形成机制,研究结果对区域水资源的可持续利用和水安全保障具有重要意义.

High-fluoride groundwater greatly threatens the security of water sources,which affects human health and ecological environment.Although a large number of studies have been carried out on high-fluoride groundwater recently,there is still a lack of systematic understanding on the geochemical background,spatiotemporal distribution changes and evolution trend of fluoride in shallow groundwater around reservoirs.Technical methods such as mathematical statistics,ArcGIS spatial interpolation,Piper plots,end element diagram,Gibbs diagram,and MINTEQ geochemical modeling were comprehensively employed to investigate the spatiotemporal distribution characteristics and impact mechanisms of fluoride(F-)in the shallow groundwater around Xianghai Reservoir.The results shows that:①The content of F-in shallow groundwater around Xianghai Reservoir is relatively high,ranging from 0.20 to 5.18 mg·L^(-1),with an average concentration of 1.76 mg·L^(-1),which is higher than the concentration limit of 1.00 mg·L^(-1) specified in the Chinese Standard for groundwater quality(GBT 14848—2017).The shallow groundwater around Xianghai Reservoir belongs to high fluorine groundwater,and the F-concentration is the highest in the northwest region,the second in the southeast region,and the lowest in the northeast and southwest region.②The chemical composition of high fluoride shallow groundwater in this area are complex,mainly consisting of HCO3-Na,HCO3-Na∙Ca,and HCO3-Na∙Mg.③The concentration of F-is closely related to the regional aquatic chemical environment.The dissolution of fluorine-containing minerals jointly caused by physicochemical processes such as evaporation,water-rock interaction and cation exchange,contributes to the enrichment of F-in local groundwater.The study clarified the spatial distribution characteristics and the formation mechanism of high-fluoride shallow groundwater around Xianghai Reservoir.The results are of great significance to the sustainable utilization of regional water resources and assurance of water security.