Abstract: The principal component analysis (PCA) model is applied to analyze the variation law of the contents of 11 trace elements in 20 soil samples collected in the Shuangtai River outfall in Liaoning Province. It is proved that Mn, Zn and Rb are the main elements which varied to the most extent. From the diagram of the content variation of Mn, Zn and Rb, it can be found that the contents of the three trace elements decrease with the distance to the blockingsea water dam and the closer the mudflat soil to the dam, the higher the content of Mn, Zn and Rb it contains. In the study area, the contents of Mn, Zn and Rb in the outfall take up 47.6%, 64.3% and 78.5% of the mudflat soil samples respectively, which indicates that the sediments in river water origined from two sources: the mud and sand in the river deposit in outfall and the colloid in the river gel through gelation in the estuary.

Key words: mudflat soil, trace elements, Shuangtai River outfall, principal component analysis