Concentration of 137CS in seawater surrounding East Malaysia

Studies of Cs-137 distribution in East Malaysia were carried out as part of a marine coastal environment project. The results of measurements will serve as baseline data and background reference level for Malaysia coastline. Twenty-one locations were identified along the coastline of East Malaysia, and from each location water samples were collected at the surface of the seawater. Ten near-shore locations were also selected and seawater was collected at three different depths. Large volumes of seawater were collected and the co-precipitation technique was employed to concentrate cesium. A known amount Of Cs-134 tracer was added as yield determinant, followed by addition of copper(II) nitrate salt and a solution of potassium hexacyanoferrate(II) trihydrate, to precipitate the total cesium. The precipitate slurry was oven dried at 60 degrees C for 1-2 days, finely ground and counted using gamma-ray spectrometry. The activity Of Cs-137 was determined by measuring the peak area under the photopeak of the gamma-spectrum at 661 keV, which is equivalent to gamma-intensity corrected for detection efficiency, percentage of gamma-ray abundance of the radionuclide and recovery of Cs-134 tracer. There were no significant differences Of Cs-137 activities both in surface and bottom water samples at 95% confidence level. The activity Of Cs-137 (for all samples) was found to be in the range of 1.47 to 3.36 Bq/m(3) and 1.69 to 3.32 Bq/m(3) for Sabah and Sarawak, respectively.