Study On The Physicochemical Properties And Salinization In The Minqin Oasis Zone

Minqin oasis zone is characterized by less rainfall,large evaporation and lack of water resources,especially the degradation of the ecological environment.The groundwater resources are continuously exploited and utilized,leading to a large number of natural and artificial vegetation deaths,desertification of and salinization of the soil.And the groundwater resources seriously affect the ecological environment of human life and production.Therefore,preventing the soil salinization and protecting the land resource is one of the important topics in the sustainable development of human life.In this paper,relying on the Minqin Oasis and along the direction of the shiyang river basin,the author collects soil samples with different depths and water samples,and the following conclusions are drawn:?1?The chemical characteristics of surface water and of groundwater are significantly different in different soil layers.In the lake area,the salinity of groundwater decreases from top to bottom in the vertical direction.The chemical characteristics of groundwater present a strong spatial autocorrelation.From 2005 to 2017 years?2005,2008,2017?,the TDS of groundwater of Xuebai Township,of Daba Township,of Datan Township,of Quanshan Township,of Hongshaliang Township and of Xiqu Township gradually decrease.From 1960s to 2011,the TDS of groundwater showed an increasing trend.?2?In 1987,1994,1998 and 2000,the saline land area of Minqin Oasis zone showed a decreasing trend.The physical indexes of soil layers of different depths have significantly different variation characteristics.In the soil layers of 0-25cm,the moisture content,the liquid limit and the plastic limit show the moderate self-correlation.And other physical indexes show the strong spatial self-correlation.In the soil layers of 25-50cm and of 50-75cm,the Co/?Co+C?values of all physical indexes are less than 25%,which have the strong spatial self-correlation.In different soil layers,the p H of each soil layer belongs to weak variation and the NO₃^-of each soil layer belongs to strong variation.And the chemical indexes of and ions of other soil layers belong to moderately strong variation.There are obviously different spatial self-correlation between chemical indexes and ions in different soil layers.?3?There are two types of soil salt including the topsoil pattern and oscillation pattern in the vertical direction,and the two types are based on the topsoil pattern.In the study area,the soil types are all the chloride-sulfur acid.Along the direction of the basin,all ions increase in the soil?except for the NO₃^-?and the types of the soil develop from non-salinized soil to saline soil.There is a significantly positive correlation between TDS of and ions of the soil?except for the NO₃^-?,and there is a significantly positive correlation between all ions?except for the NO₃^-?.?4?The soil salt content rises with the increase of salinity of groundwater,of clay,of specific surface area in soil particles and of liquid and plastic limit.Along the direction of the basin,the specific surface areas of each soil layer gradually increase.