| Abstract
| - Metal accumulation by Juncus maritimus and the role ofthis plant on the physical and chemical composition ofsediments, from the Douro river estuary (NW Portugal), wereinvestigated. The contents of Cd, Cr, Cu, Fe, Mn, Ni, Pb,and Zn were determined (by atomic absorption spectrophotometry) in sediments, rhizosediments (those amongplant roots and rhizomes), and different plant tissues (roots,rhizomes, leaves, and stems). Metal fractionation insediments through sequential extraction was carried outand used for interpretation of sediment/J. maritimusinteractions. Two estuarine sites with different characteristicswere studied: site I displayed sandy sediment withlower organic matter and metals more weakly bound to itthan site II sediment, which was muddy. At both sites,higher metal contents were observed in rhizosediments thanin the surrounding sediment, but metals were moreweakly bound to rhizosediment. Therefore, J. maritimusmarkedly influenced the sediments among its roots andrhizomes, changing metal distribution and speciation. Differentpatterns of both metal uptake and metal distributionamong J. maritimus tissues were observed at the twosites. Plant bioaccumulation was only observed for Cd, Cu,and Zn, being similar for Cd at the two sites and significantlyhigher for Cu and Zn (9 and 4 times higher, respectively)at site I. In conclusion, J. maritimus was shown to havepotential for phytoextraction (or phytostabilization) of Cd, Cu,and Zn in estuarine environment. However, an eventualapplication of J. maritimus for this purpose will require aperiodic removal of the plants together with their ownrhizosediment.
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