Analysis of the Characteristics of Soil and Groundwater Salinity in the Lower Reaches of Heihe River

Using field investigations and chemical analyses(including 405 soil samples and 101 water samples),the evolution of soil salt with groundwater quality and the location change in the lower reaches of Heihe River were made clear.The soil is coarse,and the salt content is high with high surface concentration in Ejin delta.In the study area,land desertification and land salinization is serious,land resources decrease rapidly,and ecosystem environment deteriorates seriously.Soil salinity has a funnel distribution in the vertical section and it became complicated with topography changing;however,its changing trend is similar to the groundwater quality.The salinity of groundwater is usually high,varying from 800 mg·L~-1 to 3000 mg·L~-1.The main water chemical types are HCO_3·SO_4-Na,Cl·SO_4-Na(Ca),HCO_3·Cl-Na(Ca)SO_4·Cl-Na and SO_4·Cl-Na(Ca-Mg).Analyses of the samples from two longitudinal profiles(a-a' and b-b') show that the salinity of groundwater is close related with the distance to the river course.The far to the river course is,the high the salinity is,and the vice versa.