Salinity characteristics of shell sand and adjacent ordinary saline soil was investigated in the shell ridge island of the Yellow River Delta. Spatial variability of salinity in the shell ridge was analyzed. Salinity characteristics of the profiles of two types of soil (shell sand and saline soil) with different groundwater depth were measured

the influence of soil types and groundwater depth on soil salinity was analyzed

and soil salinity characteristics was comprehensively evaluated by performing principal component analysis. The result showed that: (1) All salinity indexes

except Ca2+

showed a gradual increasing trend from surface to lower layer in the shell sand profile (0—120 cm)

but Ca2+ showed a gentle decreasing trend in the profile. (2) Content of salt ions had close relationship with groundwater depth in the shell sand profile (0—120 cm)

with the fine particle content

water content

salt content

pH value in the seaward profile (groundwater depth 1.5 m) being higher than that of the chenier ridge profile (groundwater depth 2.5 m); content of salt ions showed different trends in the two types of profiles

i.e. K+?Na+?Cl-、SO42- content of each layer (every 10 cm as a layer) in the seaward profile was obvious higher than the content of the same layer in the chenier ridge profile

but Ca2+?Mg2+ content of each layer was similar in the two profiles. (3) Correlation analysis of soil salinity indexes showed that

all indexes

except Ca2+

had significant positive correlations between each other. (4) Results of the principal component analysis showed that the cumulative contribution rate of the first four principal components reached 84.265%

which represented the saline condition

soil Ca2+ content

soil salt content and alkalization characteristic

and K+ content sequentially. Principal component analysis based on the salinity characteristic indexes could well classify and sort soil samples in the shell ridge island.