Trace metals in fluvial sediments of the Madeira River watershed, Amazon, Brazil

Abstract

Sediment samples from 10 rivers of the Madeira River watershed, Amazon, were analyzed for major and trace element composition. Differences among river classes (white, clear and black water) were detected, in particular regarding the organic matter content, the concentration of bioelements, and the trace metals Fe, Mn, Cu and Zn. This shows that the classical differentiation of Amazon rivers based on water chemistry is also confirmed by sediments. Sequential extraction oftrace metals showed that the lithogeneous and reducible fractions of sediments are the principal substrates of trace metal transport in these fluvial systems