ELEMENTAL COMPOSITION OF SUSPENDED SEDIMENTS FROM THE CHANGJIANG RIVER AND ITS ENVIRONMENTAL IMPLICATION

The study on the concentrations of major elements in the suspended sediments collected from the Changjiang mainstream at Chongqing and the downstream areas reveals that element concentrations are different in the acid leached and residual fractions. The percentages of Ca and Mg are high in the leached fraction, while Al, Fe, K and Na are mainly concentrated in the residual fraction. The compositions of major elements show somewhat regional pattern of variations, primarily reflecting the controls of sources of the weathered materials, weathering intensity and hydrodynamics of the river. The distribution of heavy metals suggests that Pb, Zn, Co and Cu accumulate in the suspended sediments, probably due to the contamination of the river by intense human activities around the Three Gorges Reservoir and its downstream areas. The instability of hydrodynamic environment in the Three Gorges Reservoir leads to the compositional variation of heavy metals in vertical profiles.