Environmental radioactivity of the St. Martin's island of Bangladesh

The activity concentration of natural and anthropogenic radionuclides in soil and rock, and in benthic algae, corals and oysters across the St. Martin's island of Bangladesh were investigated together with physicochemical parameters and texture of soil with an aim of evaluating the radioecology of the island. Soil and rock samples from the twenty-two locations of the island, eleven species of benthic algae, six species of corals and two species of oysters were analyzed. The activity of 226Ra in soil was found in the range of 7.22-103.8, in benthic algae 2.5-9.7, in coral 5.5-10 and in oyster 4.2-11.5 Bq kg-1. The activity of 232Th in soil was found in the range of 14.56-216, in benthic algae 1.3-12.6 in coral 4.4-15.6 and in oyster 3.2-8.4 Bq kg-1; and the activity of 40K in soil was in the range of 322-732, In benthic algae 17.1-45.5, in coral 21-146 and in oyster 24-32 Bq kg-1. The external radiation dose rate due to activity concentration of natural radionuclides in soil was assessed. The activity of anthropogenic 137Cs was found below detection limit. (author)