GEOCHEMICAL DYNAMICS OF HEAVY METALS IN THE SEDIMENTS OF HOOGHLYMATLA ESTUARY – A REVIEW

Estuarine sediments, especially the mangrove-dominated ones, are prone to accumulate several trace metals. The Hooghly-Matla estuary is such a unique ecosystem where anthropogenic influences pollute the pristine mangroves and the adjacent estuarine sediments. The present review collated all data acquired so far in the last two decades (2000 to 2021) and computed the composite mean concentration, and analyzed the spatial variability of nine selected heavy metals (As, Cd, Cr, Co, Cu, Fe, Pb, Hg, and Ni) in this region. The meta-analysis revealed that As and Cd are the worst polluters in these estuaries, followed by Hg and Pb. A minimal anthropogenic influence is observed in the case of Co, Cu, Cr, Ni, and Fe. Spatially, the lower end of the Hooghly Estuary and the fringe sediments situated in the mangrove forest-human habitat conjunction are the most susceptible towards heavy metal accumulation. The overall pollution load in this estuarine complex was found to be moderate; however, the magnitudes of the pollution indices indicated that in the absence of adequate policy intervention towards pollution abatement the scenario can irreversibly worsen in the near future.