• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.2
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• pp.25-34
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• 2001

/sup 226/Ra and /sup 228/Ra analysis were carried out at the representative station of Masan Bay from May to August, 1999. The high activities of /sup 226/Ra and /sup 228/Ra in the surface water were appeared in rainy season (August, 1). However, there is no significant variation in concentrations in the other season. A high negative linear correlation between /sup 226/Ra activities and salinity in the surface water suggests that /sup 226/Ra activity in the surface water was controlled by simple mixing between the two end-members low salinity high /sup 226/Ra activity water of inner Bay and a high salinity low /sup 226/Ra activity water of the continental shelf water out of Bay. /sup 226/Ra activities below the surface mixed layer were higher than those of expected level from the /sup 226/Ra versus salinity. And also /sup 228/Ra//sup 226/Ra ratios in the bottom water were lower compared to those in surface water due to the presence of potential source of /sup 226/Ra below the surface mixed layer. However, it is known that /sup 228/Ra compared to /sup 226/Ra is enriched in bottom sediments and pure water. Therefore, the most probable sources for low /sup 228/Ra//sup 226/Ra activity ration is submarine ground water discharge. Further studies are required to quantify the various sources of /sup 226/Ra and /sup 228/Ra and their relative contributions.

• Analytical Science and Technology
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• v.28 no.3
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• pp.228-235
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• 2015

The efficiency and applicability of the solid phase extraction disk method in a ²²⁶Ra analysis were examined by the gamma ray spectrometer (GRS) method using a Marinelli beaker and the liquid scintillation counter (LSC) method for groundwater. The recovered ²²⁶Ra, which was filtered by the solid phase extraction disk, was analyzed using gamma ray spectrometer The disks, which were pretreated for caulking the daughter nuclide, were sealed with polyethylene film. Distilled water was used for the blank value of the ²²⁶Ra activity. The recovery values of ²¹⁴Bi and ²¹⁴Pb in the solid phase extraction disk, which used ²²⁶Ra standard material, were 80% (295.21 Kev) and 104% (351.92 Kev), respectively, which were higher than 75% determined by the LSC. The injection of nitrogen gas into the measuring chamber reduced the interference values by about 10%. The detection limits of the ²²⁶Ra activity in a blank sample of 5 L were 0.17~0.40 pCi/L after 80,000 seconds of measuring time. The relationship of the ²²⁶Ra activity in the solid phase extraction disk method and in the LSC method in seven groundwater samples showed a correlation coefficient value 0.987, which implies the applicability of the solid phase extraction disk method. The results showed that ²²⁶Ra activity in groundwater using the solid phase extraction disk method has the following benefits: simple pretreatment, time saving, high recovery values, a low detection limit, and so on. Compared with the LSC method and the GRS method using the Marinelli beaker for the ²²⁶Ra analysis, the solid phase extraction disk method could be useful in groundwater samples with low levels of activities of radionuclides because the method is not restricted by the volume of the sample.

• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.159-164
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• 2018

An evaluation of various radiometric methods to analyze $^{226}Ra$ in water has been employed on a set of 10 standard solutions of different concentrations in the range of $1-10Bq/L^{-1}$. The analysis was carried out using well-established procedures by means of gamma-ray, alpha-particle and liquid scintillation spectrometry. The feasibility of the various methods has been quantified in terms of relative standard error and percentage error. Correlations between the various methods have been presented and discussed. In general, good agreement was found in the results of various methodologies, which assures the accuracy of the methods and allows for the validation of instrumentation and procedures. Of the different methods adopted here, a combined procedure for the determination of $^{226}Ra$ along with $^{228}Ra$ using Quantulus 1220 ultra-low level background liquid scintillation counting gave the most accurate results.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.175-182
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• 1998

Recently it is reported that anomalously low saline surface waters (salinity < 32) occurred at the Ulleung Basin in the East Sea-Japan Sea, during early September to November 1996. Apparent source of such a low saline watermass seems remotely linked to the Changjiang Dilute Water (CDW), which expands to the vicinity of Cheju Island during a flood season. Based on the assumption that waters passing through the Western Channel of the Korea Strait are formed by a mixing of Kuroshio Water and CDW, simplified two end-member mixing model using $^{228}Ra/^{226}Ra$ as a conservative tracer is applied to calculate the contribution of each end member for the formation of low saline surface seawater. Model calculations show CDW contributes $58{\pm}3%$ in September 1996 (S=32.17) and $10{\pm}3%$ in February 1997 (S=34.53) in the formation of surface water flowing into the Western Channel of the Korea Strait. Although results arc deduced from a simplified model with limited data, this study demonstrates that Changjiang discharge is clearly traceable to the interior of the East Sea-Japan Sea in fall season. Undergoing Three Valley Dam construction in the Changjiang River would invoke inevitable changes in the nature and discharge of CDW and its impacts on the marine environment might be significant in the northern East China Sea and even in the Ulleng Basin for coming decades.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.4
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• pp.305-311
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• 1999

This study aims to decipher surface water mass interaction in summer in the South China Sea and East China Sea by radium isotope distribution pattern. Salinity and activity ratio of radium ($^{228}Ra/^{226}Ra$) showed gradual changes, which were adequate to apply simple two end-member mixing between Kuroshio surface water and Changjiang Dilute Water for the East China Sea and the former and Nearshore Diluted Watermass (NDW) for the South China Sea. Two tracer methods, salinity and Ra isotope ratio, were compared for East China Sea. Results showed remarkable consistency for waters near Kuroshio, however, discrepancy were noticeable after Tsushima Warm Current branching. Mixing with subsurface waters may cause the discrepancy. When mixed with subsurface waters, salts and radium isotope ratio are expected to be biased in opposite direction, i. e. prone to underestimate the fraction of less saline water in the case of salts and vice versa for Ra isotope ratio. Taking the mean values of two different results seems more realistic to estimate fraction of end-members.