Trace elements and pedogenic changes in the Holocene Loess soil on the Changchengyuan Loess tableland in Ningxia

Based on field survey,a very typical Holocene loess-soil sequence was found on the Changchengyuan loess tableland in Pengyang,Ningxia. Samples were taken from the profile after detailed observation of the pedo-stratigraphic characteristics. The contents of V,Co,Ga,As,Y,Nb,La,Ce,Th and U were determined by X-Ray fluorescence method. Relationship between trace elements and pedogenic changes in this profile was studied. It is noted that the trace elements including V,Ga,As,Y,Nb increased in the middle Holocene paleosol (S0) because of the pedogenesis under the warm-humid climate conditions. The decrease of Th and U,and increase of V and As in the transitional loess were caused by the leaching and deposit of carbonates below the palaeosol layer.