DISTRIBUTION AND BIOACCUMULATION OF 210Po AND 210Pb IN ABIOTIC AND BIOTIC COMPONENTS OF THE BAY OF BENGAL.

Abstract

Marine environment is enriched source of heavy minerals associated with radionuclides which are largely responsible for human exposure to radiation. Bay of Bengal is one among the important marine ecosystems in the world because of its high biodiversity. The aim of this work was to generate a comprehensive data on distribution and bioaccumulation of 210Po and 210Pb in marine environment of the Bay of Bengal. For this water and sand samples (10 stations), shellfishes (21 species) and fishes (43 species) were collected and the concentrations of 210Po and 210Pb were measured by radiochemical separation followed by alpha counting method using ZnS(Ag) detector. 210Pb concentration in the marine water (mean: 7.6 ± 3.31 mBq l-1) is always higher than 210Po (mean: 4.1 ± 1.97 mBq l-1). The mean 210Po and 210Pb concentration in sand was 5.2 ± 1.87 and 3.1 ± 1.20 Bq kg-1, respectively; indicating that 210Po concentrations in the sand sample is always higher than that of 210Pb. The concentration of both 210Po and 210Pb depends on grain size of the sand. Surface samples of depth 0-10 cm recorded maximum 210Po (6.37 Bq kg-1) and 210Pb (4.07 Bq kg-1) concentration. The concentrations of 210Po and 210Pb in biota are following decreasing order: Oyster > Clam > Squid > Crab > Prawn > Fish. The committed effective dose rate calculated for shellfish species maintained a higher range of 81.0-281.2 μSv y-1. However, dose transfer rate from fish species fluctuated from 14.4 to 165.6 μSv y-1and this indicated that fish is radiologically safe as compared to shellfish.