Hydrochemical Evolution Characteristics of Groundwater at Different Depths in the Yinchuan Plain
In order to explore the hydrochemical characteristics and evolution process of groundwater at different depths(5-600 m)in the Yinchuan Plain,a systematic analysis was conducted on the hydrochemical and isotopic characteristics of groundwater at 9 different depths in the study area by using groundwater level dynamics,Person correlation analysis,saturation index,and hydrochemical methods(Piper plot,Gibbs plot and ion ratio coefficient).Besides,the tritium and 14 C dating methods were used to estimate the ages of shallow(5-30 m)and deep groundwater(150-600 m).The results indicate that the chemical types of shallow groundwater in the study area are Cl·SO4-Na·Mg or SO4·Cl·HCO3-Na·Mg,which are mainly affected by evaporation and fractional crystallization.Deep groundwater in 150-300 m and 400-600 m is HCO3·CO3-Na·Mg or HCO3-Na·Mg,which are controlled by rock weathering.Isotopes indicate that shallow groundwater is significantly recharged by irrigation water,with groundwater ages ranging from 9 a to＞68 a.Deep groundwater in 150-600 m originated from the western mountainous areas,with ages ranging from 7 325 a to 25 554 a.The ion ratio coefficient method and saturation index indicate that ions in groundwater mainly comes from weathering and dissolution of carbonate,evaporite,and silicate rocks.Cation exchange also affects the changes in chemical components in groundwater.
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维普
