[en] The age of a deep-sea clam, Tindaria callistiformis, from 3800 m depth has been determined by ²²⁸Ra(6.7 year half-life) chronology of separated size fractions of a captured population. A length of 8.4 mm is attained in about 100 years. Shells of this size fraction show about 100 regularly spaced bands, indicating that the growth feature may be an annual one. (auth)

No abstract available

[en] The present occurrence of ²²⁶Ra and ²²⁸Ra in marine sediment core and fish from the Exclusive Economic Zone in the east coast of Peninsular Malaysia were studied. Sediment core and biota in respectively was collected using multicorer device and purchased from local fishermen at identified stations during the cruise expedition conducted in 2008. The purpose of this study was to determine and to make available an inventory of activity concentration levels and activity ratio for these radionuclides in this region. The activity concentrations of ²²⁶Ra and ²²⁸Ra in sediment core and edible part of fish were ranged between 15.9-46.5 and 27.7-87.1 Bq/kg dry wt and; 0.80-2.13 and <0.95-3.57 Bq/kg fresh wt, respectively. Meanwhile, the activity ratios of ²²⁸Ra/²²⁶Ra in sediment core and fish were varied with the range between 1.63-2.09 and 0.45-2.38, respectively. Refer to those ranges the activity concentrations of radium isotopes were comparable with other region. Thus, it can be concluded that the occurrence of radium isotopes mainly supplied from terrestrial sources and the factors of assimilation efficiency and transfer coefficient of radium may probably effect to the variation activity concentration of ²²⁶Ra and ²²⁸Ra and its activity ratio in edible part of pelagic and demersal fish obtained in this study. (author)

No abstract available

[en] Surface samples of sea water collected from the Seto Inland Sea and the Japan Sea were analyzed for radium isotopes by using γ-ray spectrometry and ²²⁸Th milking method. The concentrations of ²²⁸Ra in the Seto Inland Sea water ranged from 839 to 417 dpm/1000 l and were much higher than those of open ocean water. The Inland Sea water contained ²²⁶Ra ranging from 190 to 134 dpm/1000 l and was somewhat enriched in ²²⁶Ra as compared with the Pacific Ocean Water. In the Kii Channel ²²⁸Ra concentrations of surface water varied from 333 to 48 dpm/1000 l and generally decreased away from the Inland Sea. It is suggested that the distribution of ²²⁸Ra in the Seto Inland Sea is influenced by the inflow of open ocean water from the Kii and Bungo Channels. (author)

No abstract available

[en] After radiochemical cleaning of radium, a solution with sodium salicylate as wavelength-shifting compound is measured. The chemical yield is determined using barium carrier. With high counting efficiency a lower detection limit of 0.44 pCi/sample can be achieved, using a counting time of 1000 min. Disturbances by Ra-226 and Ra-224 can be prevented by simple means. The application of the method to standard samples and the comparison with other methods demonstrated good results. (orig./HP)

[en] Surface sediment samples were collected at the West (east coast and west coast of Peninsular Malaysia) and East (Sabah and Sarawak) Malaysia in several expeditions within August 2003 until June 2008 for determining the level of natural radium isotopes. Activity concentrations of ²²⁶Ra and ²²⁸Ra in surface marine sediment at 176 sampling stations were measured. The activity concentrations of both radionuclides in Malaysia (East and West Malaysia) display varied with the range from 9 to 158 Bq/kg dry wt. and 13 to 104 Bq/kg dry wt., respectively. Meanwhile, the ratio distributions of ²²⁸Ra/²²⁶Ra were ranged from 0.62 to 3.75. This indicated that the ratios were slightly high at west coast of Peninsular Malaysia compared to other regions (east coast of Peninsular Malaysia, Sabah and Sarawak). The variation of activity concentrations of ²²⁶Ra and ²²⁸Ra and its ratios were also supported by the statistical analyses of one-way ANOVA and t test at 95 % confidence level, whereby there were proved that the measured values were different between the regions. These different were strictly related to their half-life, potential input sources (included their parents, ²³⁸U and ²³²Th), parent's characteristic, the geological setting/formation of the study area, environment origin and behavior. (author)

[en] Radium was identified as a significant environmental pollutant in the 1950s and since then has been primarily studied due to its hazard to human health. There are four naturally occurring radium isotopes, of these radium-226 ("2"2"6Ra) and radium-228 ("2"2"8Ra) have been the most widely studied as they are the most radiotoxic. "2"2"8'Ra is of main concern in IREL, OSCOM as it is the decay product of "2"3"2Th and the ore of which (Monazite) is processed here. The concerning reasons for "2"2"8Ra are: its relatively short half-life, emitted beta particles have a high potential for causing biological damage, short lived alpha-emitting daughters will build up over approximately 10 years if "2"2"8Ra is trapped in the body. Determination of "2"2"8'Ra has been an important part of the monitoring and research program of the Environmental Radiological Laboratory of HPU, IREL, OSCOM

[en] Improvements in the analyses of ²²⁶Ra and ²²⁸Ra in seawater made possible by better extraction and processing techniques reduce significantly the errors associated with these measurements. These improvements and the extensive sampling for Ra isotopes conducted on the TTO North Atlantic Study should enable us to use the distribution of ²²⁸Ra to study mixing processes on a 3-15 year time scale in both the upper and deep North Atlantic. The ²²⁸Ra profiles already analyzed show a closer resemblance to GEOSECS tritium data than to TTO tritium data in the upper ocean. This is because the transient tracer tritium was responding on a 10-year time scale during GEOSECS and a 20-year time scale during TTO. The steady state tracer ²²⁸Ra should always respond on a time scale of 8 years. Thus the ²²⁸Ra data obtained on TTO should provide a means to extend the features of the GEOSECS tritium field to the regions of the TTO study. The ²²⁶Ra data are of high enough quality to identify features associated with different water masses. Changes in the positions of the deep-water masses since the GEOSECS cruise are revealed by the ²²⁶Radata