Program
 
General Session 4: Marine environment, ecosystem & sustainability
 
 
 
Poster
Phytoremediation of trace metals from rhizosediment by native mangrove plants of Indian Sundarban Wetland
GS4-07-S
Ranju Chowdhury* , Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700019, India.
Reshmi Das, Earth Observatory of Singapore, Nanyang Technological University, 639798 Singapore
Santosh Kumar Sarkar, Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700019, India.
Presenter Email: onlyrickey@hotmail.com
The concentration of nine trace metals (As, Cd, Cr, Co, Cu, Fe, Mn, Pb and Zn ) was determined by ICP-MS in rhizosediment and different organs (leaf, bark and root/ pneumatophore tissue) of fourteen mangrove plant species from four study sites of Indian Sundarban Wetland, a UNESCO world heritage site. The study was undertaken with the following objectives: (i) to investigate the extent of accumulation and distribution of trace metals in plant tissues (ii) to determine whether sediment trace metal levels are correlated with plant tissues and (iii) to find out the suitable candidate for phytoremediation species. Triplicate rhizosediment samples along with randomly selected plant organ samples were aseptically collected, dried and grounded. Approximately 100 mg of powdered samples were dissolved in 20% inverse aqua regia and digested using microwave system (radiation power: 1200 W, 150ˇăC, 15 minutes). The extracts were diluted, filtered and analyzed using ICP-MS. In rhizosediment, trace metals followed the following descending order of accumulation: Fe> Mn>Cu> Zn>Pb> Cr> As>Co> Cd. Pollution quantification indices (index of geoaccumulation, enrichment factor, contamination factor and pollution load index) along with prescribed sediment quality guidelines showed no/very little anthropogenic stress. In plant organs, trace metals were accumulated with the following descending order: Fe> Mn>Cu> Zn> Cr>Pb> As> Co> Cd. Pneumatophore and leaf tissue accumulated maximum trace metals and gave useful information about the prevalent environmental condition. As indicated by high bioconcentration factor and (6.86) translocation factor (7.64), Avicennia officinalis was the most efficient plant as a metal accumulator by assimilating and tolerating high concentration of trace metals without showing any sigh of injury or stunted growth. This indicates its potential to act as a bioindicator plant in estuarine environment. In order to establish relationship among metals and determine their common sources, PearsonˇŻs correlation matrix was calculated which showed significant positive relation within plant tissue. One way ANOVA showed significant differences between metals (F= 586.31, P < 0.01) in plants. Cluster analysis revealed that the trace metals in the studied area mainly derived from anthropogenic activities, such as industrial effluents, agricultural waste and domestic sewage. Therefore these mangrove plants could be considered as potential metal trap to be effectively used as phytoremediator for sustainable management of this stressed coastal environment. Plantation of these mangrove plants along coastal regions not only protect the shores from different natural hazards (cyclones, storms) but also act as cleaning tools at very minimum expenditure.