Assessment of contaminants in the northwestern Bay of Bengal

The coastal sediments in the northern Bay of Bengal has undergone contamination due to the heavy metal contribution from rivers. To evaluate the status of contamination in the inner shelf region of the Bay of Bengal, a sediment core chronologically constrained using ²¹⁰Pb dating technique from the northwest Bay of Bengal was investigated for several trace elements. To assess sediment quality, enrichment factor (EF), geo-accumulation index (Igeo), and Modified Nemerow Pollution Index (MPI) were derived. The influence on ecology by individual contaminants and combined contaminants was evaluated using the potential ecological risk factor (Erⁱ) and modified ecological risk index (MRI). The single-element pollution indices indicated that the sediment has no significant pollution by individual elements. However, the multi-elemental approach shows slight pollution in the sediment core. The ecology is at low risk by contaminants present in the sediment. Comparison of the elemental values of shelf sediment with adjacent riverine and estuarine samples demonstrates the role of estuarine environment and/or high riverine flux of sediments causing either removal or dilution of trace elements during its transport from the river to the sea.