Bioaccumulation and translocation efficacy of heavy metals by Rhizophora mucronata from tropical mangrove ecosystem, Southeast coast of India

Abstract

The present study focused on the bioaccumulation and translocation efficacy of heavy metals by Rhizophora mucronata from a tropical mangrove ecosystem. The results revealed that concentration of metals in sediments varied according to different seasons, ranging for Cd (0.07–0.85), Pb (0.43–17.49), Cu (2.88–14.87) and Zn (7.80–38.37) mg/kg. Likewise, in plant tissues metal concentration ranged 0.10–0.62 (Cd), 0.76–4.35 (Cu), 6.20–26.57 (Pb) and 1.75–61.67 (Zn) mg/kg. The elevated levels of heavy metal profiles were observed in the following pattern: Zn>Pb>Cu>Cd. Among the four metals tested Pb showed highest concentration in the mangrove associated sediment and plant tissues in all the seasons, followed by Zn, Cu and Cd. In addition, bioaccumulation and translocation of Pb from the sediment to the plant tissues were relatively higher than other elements and ranged between 1.08–1.36 (BAF) and 0.96–1.29 (TF). The utilization of metals present in the surrounding medium of R. mucronata in Muthupet mangrove depends on the nature of the metal and seasonal changes. Also, the presented concentration of metals in plant tissues were several folds higher than the WHO recommended levels for plant protection, but the concentrations recorded in the sediment samples were much lesser than the sediment quality guideline. Having better accumulation and translocation rate of Pb R. mucronata could be used as bio-indicator for monitoring Pb pollution in Muthupet mangrove ecosystem.