Distribution and speciation of heavy metals in surface sediments from Guanting Reservoir, Beijing.

Surface sediments in Guanting reservoir of Beijing were studied to evaluate the heavy metal pollution. The concentrations of heavy metals lie in the sequence: Zn > Pb > Cr > Cu > Ni > Co > Mo > Cd. Significant relationship (p<0.01) between the elements Cr, Ni, Co, Cu and Ni indicates that they derived from a common geological origin. While the elements Zn, Pb and Cd correlate each other. Speciation analysis showed that most of the elements were found in the residual fraction. Enrichment of the elements Zn, Pb and Cd were found in the entrance of the rivers to the reservoir and the sampling site close to the dam. The sediment size-dependent distribution and their speciation distribution in these two sites are also distinctly different from other sediment sites. All these may indicate potential pollution of elements Zn, Pb and Cd in Guanting reservoir.