Geographical variations of trace elements in sediments of the major riversin eastern China

A total of 26 geographically and hydrologically diverse sediment samples we re collected from 12 major rivers in eastern China. The <63-<mu>m fraction of the sediments was analysed for both total concentrations of Cu, Zn, Pb a nd Cd, and their associations with various geochemical phases. The geograph ical variations of sediment-bound trace metals can be related to the bedroc k types and weathering processes in the corresponding river basins. The riv ers in southern China had notably higher concentrations of trace metals in sediments because of abundant non-ferrous mineral. deposits and stronger we athering process in the region. A large proportion of trace metals in these sediments was associated with iron and manganese oxides and organic matter . Relative low levels of trace metals were found in river sediments in nort hern China, and a significant proportion of the metals was bound to organic matter, carbonates, and the residual fraction. The sediments in the Yellow River, originating from special loess, had the lowest concentrations of tr ace metals. Most of the trace metals were associated with the carbonates an d residual phases.