Bioaccumulation of Heavy Metals Pollutants in Pichavaram Mangrove Ecosystem, Southeast Coast of India

Abstract

Studies on contaminant bioaccumulation in tropical mangrove ecosystems are very limited. An attempt has been made to assess sources of primary productivity and chemical bioaccumulation behavior in true and associated mangrove plants, water, and sediments from the Pichavaram Mangrove Ecosystem. The water, sediment, and plant materials were collected at 7 different locations and the samples were analyzed to determine the concentration of heavy metals using a flame atomic absorption spectrophotometer. The result reviles that the maximum lead concentrations of 5.48 ppm/g were accumulated in sediment samples collected from shrimp pond effluent and 4.26 ppm/l from water during post-monsoon. The maximum Zinc concentration of 12.34 ppm/g was observed in sediment samples collected from degraded mangrove forests during post-monsoon and 10.99 ppm/g was observed in sediment samples during the summer season. Higher heavy metals concentration was observed during spring and summer this may be due to increased biological activities, land runoff and rainfall during these seasons. The maximum Copper concentration 9.07 ppm/g was observed in sediment at degraded mangrove forest during post-monsoon and 8.16 ppm/g was observed in sediment during the summer season. Heavy metals concentrations in different parts of A. marina mangrove plants were analyzed. In leaf sample, Pb 5.44 ppm/g in shrimp pond effluent site,  Cd 4.97 ppm/g in degraded site, Zn 4.43 ppm/g in degrading site,  Cr 2.17 ppm/g in Freshwater zone at Vellar, Hg 1.68 ppm/g in shrimp pond effluent site, Cu 0.86 ppm/g in Freshwater zone at Upannar was recorded. In stem sample Pb 6.89 ppm/g and Zn 5.67 ppm/g in the degraded site, Cd 5.27 ppm/g in the natural site, Hg 4.91 ppm/g in degrading, Cr 2.49 ppm/g and Cu 0.87 ppm/g in Freshwater zone at Upannar was recorded. In Avicennia roots, Cr 10.89 ppm/g in shrimp pond effluent, Pb 10.17 ppm/g in natural site, Cd 6.89 ppm/g in freshwater zone at Vellar, Zn 6.86 ppm/g in degrading mangrove site, Hg 5.48 ppm/g in degraded site, Cu 0.92 ppm/g in backwater mouth was recorded. Heavy metals contamination was observed in almost all the samples in higher concentrations. The results indicate that Avicennia marina have a greater potential to observe and accumulate higher concentration than associated mangroves. A. marina plant can be used for phytoremediation to remove the heavy metals from the mangrove ecosystem and will help for ecological studies, conservation and sustainable management of the mangrove habitats.