Radioactivity in the Exclusive Economic Zone of east coast Peninsular Malaysia: distribution trends of 137Cs in surface seawater

Large volumes of surface seawater samples were collected from thirty locations in the Exclusive Economic Zone (EEZ) of the east coast Peninsular Malaysia on June 2008 to study the activity concentrations of Cs-137. The results will serve as additional information to the existing baseline data and is very useful for monitoring fresh input of anthropogenic radionuclide into Malaysian marine environment. In this study, the activity concentrations of Cs-137 were determined using co-precipitation technique, followed by Gamma Spectrometry measurement. The mean activity concentration of Cs-137 ranged between 3.40 and 5.89 Bq/m(3). Higher activity concentrations were observed at the coastal and towards the south of Peninsular Malaysia and were aligned with the high turbidity. These may due to the rapid diffusion of Cs-137 from suspended particulates and fine sediments into surface seawater. The activity concentrations of Cs-137 observed in this study were slightly higher than the concentrations reported in seawater at the Straits of Malacca, Vietnam and Philippines. This might be because the study area received more input of Cs-137 that originated from global fallout and then deposited on land which later being transported subsequently into the coastal zone due to siltation and erosion processes. It could also be attributed to the intrusion of river waters containing higher concentrations of Cs-137.