TRACE ELEMENTS GEOCHEMICAL CHARACTERISTICS OF THE SURFACE SEDIMENTS OF PEAR RIVER ESTUARY

The concentration, correlation, spatial distribution and sources of thirteen trace elements in the surface sediments from eight outles of the Pear River estuary were analyzed by multiple statistics; the factors affecting element spatial distribution were also discussed along with the comparison of the element concentration of this study with the sediments from the Pear River, shallow water of South China Sea and other areas. The mean concentration of Sr, Zn, Zr and Ba are higher than 100μg/g,while the values of Cd and Hg are lower than 1μg/g in surface sediment of Pear River estuary; the values of other analyzed elements lie within the range of 21.5~82.3μg/g. Evident correlations exist among Co, Ga, Zr; Ba, Pb, Ga and between Cu and Ni and Cr and Ni. Factor analysis indicates that weathering of land rock, artificial discharge and marine biology are the main sources of the trace elements in the surface sediments of the Pear River estuary. The spatial distribution of all studied elements except for Sr demonstrates a content decline with the distance from the shore and low values occur in some outlet areas. The source and sedimentary environment are two major factors influencing the distribution of the elements. The mean concentration of all studied trace elements aside from Zr and Sr in the study area exceeds the values from the Pear River and the shallow water of the South China Sea; the mean concentration of Pb, As, Cd and Zn in the study area are appreciably higher than the mean values of shale in the world.