Bioaccumulation Pattern of Cu, Pb and Hg in Dominant Mangroves in Indian Sundarbans Estuarine Region

Abstract

Pollution by heavy metals in coastal area especially in mangrove ecosystem in Indian Sundarbans, the world heritage site, as a result of industrialization and urbanization is a serious threat for environmental safety. This study was carried out to assess the bioaccumulation pattern of three heavy metals (copper, lead and mercury) in four dominant mangrove species from Indian Sundarbans estuarine system, namely, Avicennia alba, Avicennia marina, Avicennia officinalis and Excoecaria agallocha in the year 2014. For this purpose leaves, roots and stem samples were collected from 6 stations (viz., Chemaguri, Jambu island, Gosaba, Bali island, Sajnekhali and Bagmara) located in western, central and eastern estuarine sectors of Indian Sundarbans and analyzed for copper, lead and mercury content. The concentration of heavy metals was found in the order Cu > Pb > Hg in root, stem and leaf of the four plant species. Significant variations of heavy metal concentrations were observed between species and between stations (p < 0.01) confirming that different species has different ability of bioremediation. The pattern of bioaccumulation in the four species was seen to follow the order as A. officinalis > A. marina > A. alba > E. agallocha in all the seasons. This result indicates that A. officinalis can be regarded as the most potent bioremediator of ambient water and sediment among the four selected mangrove species.