昆明地震台流体观测井水文地球化学特征

Characteristic of hydrologic geochemistry in fluid observation well of Kunming Seismic Station

以昆明地震台井水、渔塘水为研究对象,通过水质、同位素分析方法并结合水文地质、构造地质等资料,探究井水地球化学特征及意义,以及井水与渔塘水之间的水力关系。研究结果显示:昆明地震台井水、渔塘水水化学类型为HCO_(3)—Ca型,水质受含水层和隔水层岩性控制,与2018年相比2020年井水水化学特征发生了显著变化,K^(+)、HCO_(3)-浓度降低,这反映了昆明地震台井—含水层渗透性有所增加;SO_(4)^(2-)、Cl^(-)浓度的增加则表明昆明地震台井水会受到人为干扰。研究区构造活动平稳,井水为未成熟水,演化程度较低,因含水层渗透性增强和人为干扰,自2018年7月至2020年11月昆明地震台井水—岩作用有所增强,表现为δD、δ^(18)O富集,Mg^(2+)浓度升高。井水补给来源为大气降水,补给区位于观测井正北的石关一带。渔塘水与昆明地震台井水间存在水力关系,在分析地表水对昆明地震台井的影响时应予以考虑,但渔塘水不是影响井水的主要因素。

Taking well water and fish pond water of Kunming Seismic Station as study objects,the characteristics and significance of well water geochemistry and hydraulic relationship between well water and fishpond water are studied by water quality,isotope analysis method and hydrogeology,structural geology,etc.The results show that the water chemical type of well water and fish pond water at Kunming Seismic Station is HCO_(3)^(-)-Ca type,and the water quality is controlled by the lithology of aquifer and water resisting layer.Compared with well water in the year of 2018,the water chemical characteristics of well water in the year of 2020 has changed significantly.The decrease of K^(+) and HCO_(3)^(-) concentration indicates that the permeability of well-aquifer of Kunming Seismic Station is increased,and the increase of SO_(4)^(2-) and Cl^(-)concentration indicates that the well water of Kunming Seismic Station is disturbed artificially.The tectonic activity in the study area is stable,and the well water is immature water with a low degree of evolution.Due to the enhancement of the permeability of aquifer and artificial disturbance,the water-rock interaction of well at Kunming Seismic Station has been enhanced from July 2018 to November 2020,showing the enrichment ofδD andδ^(18)O and the increase of Mg^(2+)concentration.The recharge source of well water is meteoric water,and the recharge area is Shiguan area,which is north of the observation well.There is a certain hydraulic relationship between the pond water and the well water,which should be taken into account when analyzing the influence of surface water on Kunming Seismic Station well.However,the fishpond water is not the main factor affecting well water.