To assess rare earth element (REE) distribution, fractionation during weath
ering processes and river transport, a sequential extraction procedure was
applied to 36 river sediments collected from different rivers in Argentina,
Brazil, France and Morocco. The results show that labile REE fractions are
mainly linked to carbonates, iron oxides or organic matter according to th
e river. Moreover the leached REE do not behave as a coherent group: middle
REE are mainly bound to carbonates or organic matter, whereas light REE (e
xcept cerium) are preferentially linked to organic matter and heavy REE and
cerium are associated with iron oxides. ((C) Academie des sciences / Elsev
ier, Paris.).