The presence of natural radioactivity and 137Cs in the South China Sea bordering peninsular Malaysia

The presence of natural radioactivity and Cs-137 has been investigated in fresh media obtained from South China Sea locations off the coast of peninsular Malaysia. The media include seafood, sea water and sediment. The samples were collected some weeks prior to the devastating 2011 Tohoku earthquake and associated tsunami, the occurrence of which precipitated the Fukushima incident. All samples showed the presence of naturally occurring Ra-226, Ra-228 and primordial K-40, all at typically prevailing levels. The concentrations of natural radioactivity in molluscs were found to be greater than that of other marine life studied herein, the total activity ranging from 337 to 393 Bq kg(1) dry weight. The total activity in sea water ranged from 15 to 88 Bq l(1). Sediment samples obtained at deep sea locations more than 20 km offshore further revealed the presence of Cs-137. The activity of Cs-137 varied from ND to 0.5 Bq kg(1) dry weight, the activity increasing with offshore distance and depth. The activity concentrations presented herein should be considered useful in assessing the impact of any future radiological contamination to the marine environment.