Studies of naturally occurring radioactive materials (NORM) distribution of (226)Ra, (228)Ra and (40)K 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 coastlines. Sediments from 21 coastal locations and 10 near shore locations were collected for analyses. The samples were dried, finely ground, sealed in a container and stored for a minimum of 30 days to establish secular equilibrium between (226)Ra and (228)Ra and their respective radioactive progenies. They were counted using a high-purity germanium (HPGe) spectrometer covering the respective progeny energy peak. For (40)K, the presence of this was measured directly via its 1460 keV energy peak. The concentration of (226)Ra, (228)Ra and (40)K in samples obtained from coastal Sarawak ranged between 23 and 41 (mean 30+/-2) Bq/kg, 27 and 45 (mean 39+/-4) Bq/kg and 142 and 680 (mean 462+/-59) Bq/kg, respectively. Meanwhile, the concentration of (226)Ra, (228)Ra and (40)K for samples obtained from coastal Sabah ranged between 16 and 30 (mean 23+/-2) Bq/kg, 23 and 45 (mean 35+/-4) Bq/kg and 402 and 842 (mean 577+/-75) Bq/kg, respectively. For the Sarawak near shore stations, the concentration of (226)Ra, (228)Ra and (40)K ranged between 11 and 36 (mean 22+/-2) Bq/kg, 21 and 65 (mean 39+/-5) Bq/kg and 149 and 517 (mean 309+/-41) Bq/kg, respectively. Meanwhile, the concentration of (226)Ra, (228)Ra and (40)K for samples obtained from Sabah ranged between 9 and 31 (mean 14+/-2) Bq/kg, 10 and 48 (mean 21+/-3) Bq/kg and 140 and 580 (mean 269+/-36) Bq/kg, respectively. The calculated external hazard values of between 0.17 and 0.33 (less than unity) showed that there is little risk of external hazard to the workers handling the sediments.
The concentrations of 137Cs and 134Cs in Malaysian marine sediments were measured by gamma-ray spectrometry with a high-purity germanium (HPGe) detector connected to a multichannel analyzer. In general, the 137Cs concentration in Malaysian marine sediments has been found to be very low and less than 5 Bq/kg dry weight with the exception of those from a few sampling locations. The concentration of 134Cs was found to be less than the minimum detectable activity for the measuring condition used. Data reported in this paper were found to be comparable with results from within the region and thus can be used as reference data for the country.
Laboratories from 14 countries (with different levels of expertise in radionuclide measurements and 210Pb dating) participated in an interlaboratory comparison exercise (ILC) related to the application of 210Pb sediment dating technique within the framework of the IAEA Coordinated Research Project. The laboratories were provided with samples from a composite sediment core and were required to provide massic activities of several radionuclides and an age versus depth model from the obtained results, using the most suitable 210Pb dating model. Massic concentrations of Zn and Cu were also determined to be used for chronology validation. The ILC results indicated good analytical performances while the dating results didn't demonstrate the same degree of competence in part due to the different experience in dating of the participant laboratories. The ILC exercise enabled evaluation of the difficulties faced by laboratories implementing 210Pb dating methods and identified some limitations in providing reliable chronologies.