Trace element geochemistry in topsoil from East China

Abstract

The concentrations of 23 trace elements in 50 topsoil samples collected from sites ranging between 18°19′N and 49°13′N in East China were analyzed. Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, and Ta have mean contents more than two times higher than in the continental upper crust. Three elements, Rb, Sr, and Ba, are present at lower concentrations than in the continental upper crust. Finally, a group of elements consisting of Ge, Y, Zr, Nb, Sc, Hf, Pb, Th, and U are present at concentrations 1–2 times higher than in the continental upper crust. However, concentrations of trace elements are mainly affected by parent rock. The contents of Sc, Ti, V, Cr, Mn, Co, and Cu for 29 soils from basalt were found to increase from north to south, whereas Rb, Sr, and Ba contents were found to decrease. In addition, element concentration shows a close relationship with annual average temperature (AAT) as well as annual average precipitation (AAP). Since the 29 soils are all from basalt, the trends of the elemental contents should reflect the influence of climate, which determines the intensity of weathering. These elemental trends suggest that the content of certain elements may indicate the intensity of basalt weathering. Ba/Nb and Sr/Nb ratios were both found to have good correlations with AAT and AAP in this study, which means that these ratios can also indicate the intensity of chemical weathering of basalt.