Levels of heavy metals in wetland and marine vascular plants and their biomonitoring potential: A comparative assessment

The present study investigated the levels of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn in the seagrasses Posidoniaoceanica and Cymodocea nodosa, and in the wetland macrophytes Phragmites australis, Arundo donax, Typhadomingensis, Apium nodiflorum, and Nasturtium officinale. Results showed that the bioaccumulation capacityfromsediments, translocation, total levels in plant tissues, and bioindication of metals in sediments, are generallyspecies-specific. In particular, the patterns of metals in the aquatic plants studied were overall independent ofecology (coasts vs wetlands), biomass, anatomy (rhizomatous vs non rhizomatous plants), and life form(hemicrytophytes vs hydrophytes). However, marine phanerogams and wetland macrophytes shared somecharacteristics such as high levels of heavy metals in their below-ground organs, similar capacity of elementtranslocation in the rhizosphere, compartmentalization of metals in the different plant organs, and potential asbioindicators of Cu, Mn and Zn levels in the substratum. In particular, the present findings indicate that, despiteecological and morphological similarities, different plant species tend to respond differently to exposure to heavymetals. Furthermore, this seems to result from the species individual ability to accumulate and detoxify the variousmetals rather than being attributed to differences in their ecological and morpho-anatomical characteristics.