ABSTRACT
Phytoremediation, a treatment technique for getting rid of toxic trace metal pollution is being explored for a long time owing to its low-cost compared to physicochemical methods. Mangrove estuaries are often high metal pollution due to the high affinity of sedimentary organic matter (OM) for trace metals and capacity of mangroves to efficiently trap suspended material from the water and sediments. The functionality of mangroves to store metallic pollutants have been proven to be an effective natural purification process for toxic wastewater treatment. The Hooghly estuary supporting world’s largest continuous mangrove forest, the Sundarbans have also reported significantly high trace metal pollution. Particularly Al, As, Cd, Cr, Cu, Co, Fe, Hg, Pb, Mn, Ni, V, and Zn have shown higher shale values when compared with the global standard. Regular disposal of domestic sewage, semi treated industrial effluents, surface, and agricultural run-off are the potential sources of contamination in the zone. Studies have proven some of the dominant mangroves of Sundarbans namely Avicennia officinalis, Sonneratia apetala and Excoecaria agallocha have high toxic metal phytoremediation ability. This is of particular significance as Indian Sundarbans is home to over 4.5 million people and trace metals are non-biodegradable, 132shows bioaccumulation tendency in flora and fauna and toxic on exposure above threshold limits. Agriculture is the main occupation among the inhabitants and hence a balance between mangrove population and metal toxic waste free agricultural land is of baffling importance. Lastly, the post-harvest management of phytoremediation derived waste have received scarce focus to date. Hence strategies for removal of mangrove plant biomass with concentrated metal wastes are discussed as a way forward.
