内蒙古杭锦旗气田区地下水化学特征及其形成机制

摘要

The Piper and Gibbs diagrams and alkali index are used to analyze the chemical characteristics and the formation mechanism of shallow groundwater from gas field in the Hangjinqi,Inner Mongolia.In this study,our new results suggest that the groundwater has following key features.Shallow groundwater of the study area generally has high mineralization,alkaline,brackish and great hardness;the TDS and total hardness in wet season are greater than those of the dry season.The chemical composition of shallow groundwater from the study area has a certain spatial variability on a small scale and the major cation of shallow groundwater are Na +,Ca2 +;and anion is HCO3-with the major hydrochemical types of HCO3-Na,HCO3-Ca and SO4· Cl-Na.The chemical composition of shallow groundwater originates from aluminosilicate minerals,carbonate minerals,and evaporate minerals;in addition,there is a change in chemical composition of the wet season and dry season.The formation of hydrochemical characteristics of the groundwater in study area is given priority to the rock-weathering dissolution.%对内蒙古杭锦旗气田区浅层地下水运用Piper三线图、Gibbs图、氯碱指数图等方法进行水化学特征及其形成作用分析研究,结果表明:杭锦旗气田区浅层地下水具有较高的矿化度,偏碱性,硬度较大,枯水期TDS浓度和总硬度高于丰水期;研究区浅层地下水化学组分在小范围内具有一定的空间变异性,地下水阳离子以Na+、Ca2为主,阴离子以HCO3-为主,水化学类型主要有HCO3-Ca型、HCO3-Na型和SO4·Cl-Na型;研究区浅层地下水化学组分来源于碳酸盐矿物、硅铝酸盐矿物和蒸发岩的风化溶解,且丰水期和枯水期水化学组分有微弱变化,地下水化学特征的形成以岩石风化溶解作用为主.