AN INTEGRATED MAGNETIC-CHEMICAL APPROACH TO THE STUDY OF IRON IN RHONE ESTUARY SEDIMENTS

Measurement of magnetic parameters in combination with the partitionin g of iron in various sediment fractions (authigenic-lithogenous) have been used in order to obtain information concerning the fate of iron w ithin the sediment. Through this approach, it is shown that in the Rho ne estuary sediments there is a dominance of the lattice-held iron, re presented by the abundance of ferrimagnetic minerals. A considerable p art (similar to 17 %) of the iron present is authigenic, associated ma inly with the oxide-hydroxide forms and originating from direct fluvia l inputs and in situ diagenetic processes. Iron oxides and hydroxides are formed in the water column and/or porewaters and are accumulated m ainly in the surface layer (0-2 cm) of the sediment column correspondi ng to the mineral goethite. (C) Elsevier, Paris.