Metal contamination in sediment of Hugli estuarine system has often been assessed using datasets that provide dramatic over – or underestimate of actual status of sediment contamination due to lack of stipulated guidelines for collecting sediment with respect to grain sizes. This study has been undertaken to present how the level of metal contamination in sediment can be evaluated. The analytical results focus spatial and temporal conditions of metals in 200- mm and 63-mm sediment fractions. To better elucidate actual degree of metal pollution, contamination sources, and geochemical processes; statistical analysis are employed to intensive datasets collected from Hugli estuary that discharges into the largest alluvial fan in the world. Multivariate analysis including hierarchical cluster analysis clearly identified influence of anthropogenic and natural activities on metal contamination and geochemical processes controlling level of metal contamination in sediment of Hugli estuary. Normalization of Al indicated relatively high enrichment factors for Pb, Ni, Cu, Co, Cd, Cr and Fe suggesting contamination of these metals due to anthropogenic activities. Strong seasonal change, variable tidal energy level and irregular estuarine geometry in the study area played crucial role in governing metal concentration in freshly deposited sediment. This paper sheds some lights on necessity of refining existing monitoring practice and its importance in estuarine environment management.
