Trace metal concentrations in coastal marshes of the Lower Parana River and the Rio de la Plata Estuary

Cu, Cr, Pb, Zn and Fe in water, sediment and tissue of the emergent macroph yte Schoenoplectus californicus were studied in three coastal environments differing in aquatic chemistry and tide amplitude: a deltaic floodplain mar sh, a coastal vegetated strip of the river and a tidal marsh at the south m argin of the Rio de la Plata Estuary. Metal content in water was not signif icantly different between the river and the floodplain marsh. Metal content in sediments showed higher values in the marshes than in the river, sugges ting a retention in the marsh. Except for Cu, the highest metal content in sediments and water was observed in the tidal marsh. Pb in plants was undet ectable. Metal content was higher in rhizomes, except Cr, which was mainly stored in stems. Rhizome metal content was higher in the river, probably re lated to the higher redox potential of its sediments. Inflorescence metal c ontent was higher in the marshes: the highest Zn, Cr and Fe contents were m easured in the tidal marsh; the highest Cu content was in the floodplain ma rsh, together with the highest organic matter content of the sediments. Zn, Cr and Fe increased in standing drying stems and in inflorescences in late fall. Inflorescences showed the highest metal content after seeds had been released.