Study On The Groundwater Chemical Evolution In Turpan Basin

Mathematical statistics,hydrogeochemical analysis,isotope tracer and hydrogeochemical simulation methods were used to analyze the chemical composition and ion source,the distribution features of groundwater chemical types,and evolution characteristics in Turpan Basin.The purpose of the study is to explore the relationship between the evolution of groundwater chemical environment and human activities,as well as hydrogeological conditions.This will helpful to effective use groundwater resources and protect the environment in the Turpan region.The main conclusions as follows:(1)The groundwater of the northern Basin is recharged by surface runoff in the northern mountainous region,In the piedmont zone,the chemical type of groundwater is HCO₃-Ca,The middle of the alluvial-diluvial fan is HCO₃·SO₄-Ca·Na type,and in the alluvial-diluvial fan,the edge is changed to HCO₃·Cl-Na·Ca or SO₄·Cl-Ca·Na type,while in the west,it is mostly HCO₃·SO₄-Ca·Mg type.In front of the slopes of the Southern Basin,The types of groundwater chemistry is mostly HCO₃·SO-Ca·Na type,In the plain area,Groundwater chemical types is SO₄·Cl-Ca·Na and SO₄·Cl-Na·Mg types,in the Ai Ding Lake lacustrine plain,it is mostly SO₄·Cl-Na or Cl·SO₄-Na type(2)The groundwater hydrochemistry of the northern Basin is mainly controlled by the weathering of rocks.Part of the water chemistry characteristics of the plain area are subjected to evaporative concentration.The ions in the surface water are mainly affected by rock weathering.Combined with regional geological conditions,the main weathered rocks in the area include sulfates and calcium and sodium minerals.The shallow surface groundwater of the South Basin mostly falls into the upper-right corner of the region with a Na⁺/(Na⁺+Ca²⁺)value greater than 0.5,and the chemical characteristics of the shallow surface groundwater recharge source water are also affected by the weathering of the rock and evaporation and condensation.In the vicinity of the old Dikan township on the edge of the desert in the desert of Kumuttag,the main evapotranspiration is controlled.Shallow groundwater is basically located in the middle of the Gibbs map,and is mainly rock weathering type.The groundwater located in the southern part of Lake Eden and the eastern Tuokexun Plain has a small depth of burial and strong evaporation,which is mainly affected by evaporation and condensation.(3)Based on the analysis results of hydrogen and oxygen isotopes.The results show that the?D of groundwater is between-87.88‰and-65.97,the?¹⁸O is between-9.4‰and-12.37;and the?¹⁸O of surface water is between-10.08‰and-13.63‰.between.Groundwater and surface water are homologous to atmospheric precipitation and undergo strong evaporation.Shallow groundwater mainly accepts infiltration of river water in the alluvial-diluvial fan and infiltration of river diversion irrigation.Shallow groundwater has a small depth.Evaporation is stronger than shallow water.The hydraulic relationship between different depths of groundwater is more closely related to a unified groundwater system.The enrichment of?D and?¹⁸O confirms the strong evaporation effect in the southern area of Flaming Mountain and the discharge area of Lake Aiding.(4)The results of reverse hydrogeochemical path simulations show that in the direction of the runoff along the Coal Mine Drainage Basin,precipitation reactions of calcite and dolomite,dissolution reactions of gypsum and potassium feldspar,exchange reactions of Ca-Na cations,and dissolution reactions of rock salt or plagioclase occur.