Abstract:
Sediment cores from the mangrove region of the Sal Estuary were analysed to assess the bioavailability of metals. Also, the concentration of metals in mangrove plants was measured to decipher their phytoremediation ability. The metals in bioavailable form were significant (greater than 25 percent) in core S-1 (Mn, Zn, Cu and Co), and cores S-3 and S-5 (Zn, Cu and Co). Fe-Mn oxides and organic matter/sulphide fractions mainly regulated the metal bioavailability in sediments. Screening quick reference table identified Co as toxic to biota, while the risk assessment code suggested a moderate to high risk from Mn, Zn, Cu, Co and Ni. Sonneratia alba, Avicennia alba and Avicennia marina accumulated high content of Fe, Mn, Cu, Co and Ni in pneumatophores than stem and leaves which was attributed to Fe-plaque and pyrite formations. Mangroves disclosed their applications in phytostabilization and phytoextraction techniques.
