Vertical distribution and content levels of chemical elements in the ground substrate in Shuangliao area of Horqin sandy land

This study systematically investigates the vertical distribution characteristics of major,mineral,beneficial,and harmful elements in the top 50 m of borehole SLZK04 in Shuangliao area,Jilin Province. The results reveal that the contents of Al₂O₃,CaO,MgO,TiO₂,P₂O₅,and Fe₂ O₃ exhibit a negative correlation with SiO₂ content,which is closely associated with soil texture. The distribution patterns of mineral elements generally show higher concentrations in oxidizing weathering and transport environments, whereas lower concentrations are found in reducing lacustrine sedimentary conditions. The distribution of beneficial elements is also constrained by sedimentary environments,while harmful elements maintain consistently low levels throughout the borehole. Quality assessment of chemical elements in the whole soil profile indicates that the average CaO content falls into Grade II（relatively abundant）,MgO into Grade IV（relatively deficient）,Fe₂O₃,Mn,and P into Grade V（deficient）,K into Grade III（moderate）,and Se,I,and F into Grade V（deficient）. The soil environmental quality is classified as Class I（clean）.