Journal of the Marine Biological Association of India

Volume 48 Issue 2

A radiological survey in the ecosystem of Athangarai Estuary in the Palk Strait

R. Krishnamoorthy, A.Sadiq Bukhari, M.M.Shahul Hameed, H.E.Syed Mohamed and P.Shahul Hameed

Measurements of Terrestrial Gamma Radiation, Primordial Radionuclides and Gross Alpha were made in sediment sample collected from Athangarai Estuary (9?20'41.99"N - 78'59'55.92"E) in Palk Strait. Water, sediment and selected biota were subjected to 210Po determination. The Terrestrial Gamma radiation level in the estuary was 9.4 ± 3.0m R/h. The Primordial radionuclides levels in the estuarine sediment are 238U (0.9 Bq/kg), 232Th (8.45 Bqlkg), 40K (289 Bq/kg). The Gross Alpha level in Athangarai Estuary was 6.4 m Bq.g-1. In

water, dissolved concentration of 210Po was found to be 1.2 m Bq/l and in sediment (6.3 Bq/kg). Sediment samples of six different sizes grain ranging from 50 µm to 900 pm were subjected to analysis. Particles of 900 µm registered activity between 6.9 Bq/kg and 186 Bqkg. The highest activity of 210Po 6.3 Bq/kg was in the upper layer sediment (0-5cm) and 5.3 Bq/kg at 5-10 cm and 3.8 Bq/kg at 10-15 cm. The 210Po activity in the biota was within the range of 12.3 and 345.8 Bq/kg. The bivalve mollusc Meretrix casta of the estuary was identified to concentrate higher level of 2'oPo in their soft tissues, suggesting that it could be used as a sentinel organism for 210Po in an estuarine system. The significance of the results are discussed.

Date : 30-12-2006