Heavy metal phytoremediation potential of plant species in a mangrove ecosystem in Pattani Bay, Thailand

Abstract

© 2016, ALÖKI Kft., Budapest, Hungary. In a mangrove forest in Pattani Bay, Thailand, rhizosphere soil and leaf, stem and root tissue from various plant species were tested for concentrations of Cd, Cr, Cu, Mn, Ni, Pb and Zn. Of these metals, Pb concentrations in the mangrove sediment were somewhat elevated. Mn occurred in highest concentrations in tissue of all mangrove species whereas Cd contents were lowest. Both sediment physicochemical properties (e.g., pH, EC, redox potential) and plant species characteristics have likely influenced metal concentrations in plant tissue. Several mangrove species fit the criteria for excluder plants as they accumulated metals mainly in roots, with a resultant translocation factor (TF) < 1 and a bioconcentration factor (BCF) > 1. These include Cyperus involucratus for Cu, Ipomoea pes-caprae for Zn, Typha angustifolia for Mn, and Phragmites karka for Pb. Furthermore, some species have accumulator potential, as metals accumulated in aboveground biomass (leaves and stem), and have TF > 1 and BCF > 1; however, these species (e.g., Thespesia populnea for Ni and C. involucratus for Cr) did not accumulate metals to the extent that they fit the criteria for hyperaccumulators. Continued investigation of metals in sediment and plant organs must be carried out to determine additional species suitable for phytoremediation, and to ensure healthy food chains in coastal ecosystems.