Eco-Toxic Risk Assessment of Nearshore Sediments in Bay of Bengal - Environmental Radioactivity and Ecological Risk as a Proxy

Abstract

The present study focuses on the environmental radioactivity and multi-risk assessment of nearshore sediments as a source of marine pollution along the Bay of Bengal. The study examines the distribution of primordial radionuclides concentration using a Na(I)Tl detector-based gamma-ray spectrometer and Potentially Toxic Elements (PTE) through atomic adsorption analysis. Further, the data obtained and characterization radiological risks, ecological threats, and assessing the spatial distribution of toxic elements in nearshore sediments as a proxy for marine contamination. The active concentration of primordial radionuclides such as 238U, 232Th and 40K were found in ranged from ≤ 3 to 68 (11.4), ≤ 9.5 to 142.7 (41.2) and 85.2 to 603.4 (362) Bq kg-1. Results show that the concentration of the average radionuclides is less than suggested by UNSCEAR ranges. The concentration of potentially toxic elements (Fe, Cr, Ni, Pb and Zn) was higher in deeper water depth. This study exposes that the primary control of such elements is mud distribution. A decreasing order has been seen as follows by the ecological risk index of individual elements: Cu > Pb > Ni > Cr > Zn. The significant Pb, Cu and Zn concentration was polluted at most stations, possibly contributing the regional and terrestrial sources such as industrial activity, urban drainage, manufacturing, and farming. This research suggests that anthropogenic behaviours in nearby land are the source of the deposition of metals and radionuclides in coastal and marine sediments.