Halophytes as sources of metals in estuarine systems with low levels of contamination.

Heavy metal concentrations present in the above- and beowground tissues of Scirpus maritimus L., Spartina maritima (Curtis) Fernald and Zostera noltii Hornem were analysed seasonally in the Mondego Estuary, Portugal. The sediments of the estuary were confirmed to contain only low concentrations of heavy metals.