Chemical Characteristics And Control Factors Of Multi-Type Water Resource In Shiyang River Basin

The composition of water bodies is determined by lithology,climate,and ecological environment of the rock,which is widely used to identify the controlling factor the chemical composition of water.The Shiyang River Basin is a typical basin of arid area in the Northwest China.Owing to its arid climate,distant location,and intensive agricultural production practices,the Shiyang River Basin is an excellent natural science laboratory for the environmental studies.The over-exploitation of groundwater resources in the Shiyang River Basin has led to severe aftereffects,which drew the attention of the Chinese government and a large number of scientists to groundwater evolution and recharge in the Shiyang River Basin.Therefore,it is an important exploration to study the water characteristics,spatial evolution and temporal variation of water bodies in the Shiyang River Basin,which,it is an important exploration of water resources security in the typical northwest arid area.The research can provide basic geographic data and information for regional hydrochemistry and geochemistry.In addition,the study is a leading research on the characteristics and changes of hydrological water quality under ice and snow and karst interaction.It is also an important attempt to sustainable development and utilization of water resources and ecological environment construction.A scientific field investigation was accomplished between July 2015 and June2016.The samples involve precipitation,surface water and groundwater from Wuwei basin Minqin basin.Water samples were collected and analyzed for their content of major cations(Ca²⁺,Mg²⁺,Na⁺,K⁺,and NH₄⁺)and anions(HCO₃^-,Cl^-,NO₃^-,NO₂^-,F^-,and SO₄^2-),and total solid solubility and pH values.The results showed that:?1?Precipitation,surface water,and groundwater were mildly alkaline.Ionic concentrations in the surface water and groundwater samples were in the following descending orders:Ca²⁺>Na⁺>Mg²⁺>K⁺>NH₄⁺for cations and SO₄^2->HCO₃^->Cl^->NO₃^->NO₂^->F^-for anions.On the other hand,the precipitation water samples had the following order of cations concentration:Na⁺>K⁺>Ca²⁺>NH₄⁺>Mg²⁺.Ca²⁺and SO₄^2-were the predominant ions,accounting for 47%and 75%of the total cations and anions,respectively.?2?The content of inorganic ion varied largely in the different seasons.The highest ion concentration was observed in spring,whereas its values were the lowest in summer.The seasonal variations in groundwater parameters were less considerable than those of surface water.Furthermore,the anion concentrations increased substantially from upstream to downstream.?3?The Gibbs diagram shows that the main controlling factors of water ionization in the Shiyang River Basin are rock and soil weathering.Some samples are affected by evaporation,and the effect of precipitation is small and negligible.The Piper diagram analysis finds that most of the water bodies in the Shiyang River Basin are sulfate-type water,no chloride-type water.The relative contribution of three types of rocks to the dissolved water was in the following order:silicate rock,evaporated rock salt,and carbonate.?4?Human activities also had a certain impact on the ion content.Sodium ion and normalization of NO₃^-,SO₄^2-have a positive correlation,which indicates that NO₃^-and SO₄^2-have the same or similar source.In addition,we discovered that anthropogenic inputs had led to light pollution of water in some residential district.