SALINITY ANALYSIS OF DESERT WETLAND SOILS IN EXTREMELY ARID REGIONS

The Xihu desert wetland of Dunhuang (Gansu province) has the dual features of an extremely arid desert ecosystem and wetland ecosystem and plays a particularly important role in China. However, research on soil salinity in this region is very rare. This study collected samples of different soil types in the Xihu desert wetland ecosystem and analyzed the soil salinity characteristics at different sites. This study provides theoretical and data support for the assessment of soil salinization, ecological restoration and sustainable use of desert wetlands. According to the results, of the eight types of ions in the Xihu desert wetland soils, Na+, Ca2+, Mg2+ and K+ dominate the positive ions, while so(4)(2-), Cl- and HCO3- dominate the negative ions, but CO32- was not detected. Na+ had the highest positive ion concentration, while K+ had the lowest concen- tration. Na+ was mainly present in the form of sodium and calcium salts. SO42- had the highest negative ion concentration, while HCO32- had the lowest concentration. The salinity is mainly contri- buted by Na2SO4 and CaSO4. The correlation analysis of the salt ions in the Xihu desert wetland soils suggested that there were correlations between the different salt ions in the soil and these reflected the sedimentation characteristics of the salts. The cluster analysis of soil salt ions showed that salinity analysis could be restricted to just three ions (Ca2+, Cl-, and SO42-) and these ions would sufficiently reflect the changes in the various salt contents in the Xihu desert wetland. The formation of saline soil in the research area was due to the combined actions of parent material, landform and hydrogeology.