Assessment of Human Induced Potentially Toxic Metal Aggregation and Decadal Change in Sediment Quality of River Hooghly: Implications to the Usage of Pneumatophores as a Potential Bio-indicator and Phytoremediator

摘要

Mangrove sediment acts as a natural accumulator of potentially toxic metals (PTMs). Here, we have investigated the efficiency of mangrove species, e.g., Sonneratia caseolaris and Avicennia officinalis phytoremediation potential in a globally significant vulnerable river. The lower pH and anoxic conditions facilitate the elevated accumulation of PTMs in river Hooghly. The presence of PTMs in fine sediment fraction in greater proportion indicates a larger role of fine-grained silt and clay particles in the accumulation process. The estimated sediment quality indices indicate no significant change in the last 30 years. However, the ecotoxicological indices suggest a low level of ecological risks but can turn toxic because of the gradual accumulation of metals. The accumulations of PTMs in mangroves are regulated by the metal bio-availability. The result emphasizes mangrove pneumatophores, as a greater accumulator of PTMs than mangrove leaves. Higher translocation factors also indicate the applicability of mangroves as a phytoremediator of contaminated sediment.