Hydrochemical Characteristics and Evolution Laws of Shallow Groundwater in Shuangliao City

Shuangliao City is an important part of the Xiliaohe Plain, and one of the most important bases of grain production in the north of China. Therefore, it is important to ascertain the hydrochemical characteristics of groundwater and their causes and evolution laws in the Xiliaohe Plain to provide guidance to agriculture development and ecological improvement. After collection of detailed data and identification of the groundwater flow field, we studied the causes and evolution of the identified hydrochemical types by zone with mathematical statistics, correlation analysis, ion proportional coefficient and other methods. The results show that the concentrations of HCO3-, Cl-, and Na+ are relatively high, and these of Ca2+, Mg2+, SO42-, and NO3- are relatively low. The concentration of TDS increases gradually along the flow direction of groundwater, and TDS is positively correlated to the variation in concentration of Cl-, Na+, Mg2+, and SO42-. Along the flow direction of groundwater, the hydrochemistry of shallow groundwater show the evolution law from HCO3-Ca·Mg to HCO3·Cl-Na·Ca and HCO3·Cl-Na·Mg, and then to Cl·HCO3-Na·Mg. The hydrochemical types are formed mainly due to the mineral dissolution and deposition, and reaction of cation exchange and adsorption in the aquifer, and the hydrogeochemical processes include leaching, evaporation and concentration, and mixing.