This paper reports the distribution of natural radionuclides of 224, 223Ra in the surface water and stratified waters of the Luzon Strait and its adjacent waters during the cruises of September 2015 and May 2016. To u...This paper reports the distribution of natural radionuclides of 224, 223Ra in the surface water and stratified waters of the Luzon Strait and its adjacent waters during the cruises of September 2015 and May 2016. To understand the impact of the Fukushima nuclear accident, the artificial radionuclide 137Cs in the waters was also analyzed. The results showed that the activities of 224, 223Ra and 137Cs were all within the natural radioactive background levels of the marine environment in the South China Sea. 224Ra had a higher activity level in the water of the north South China Sea to the west of the Luzon Strait, and a lower activity level in the oceanic Philippine Sea to the east. The137Cs activity had no obvious spatial trends. Based on the vertical trends of 224Ra, 137Cs, and water temperature and salinity at three stations(LS3, LS5 and LS8), the distinct characteristics of the activity levels and gradients of224Ra and 137Cs among the tropical surface water, subsurface water and mid-deep water were revealed. Typhoon Rainbow event reversed the overall circulation of the Luzon Strait and its adjacent area. A huge amount of western Pacific water characterized by low 224Ra activities flooded into the South China Sea, reducing the activity level of224Ra in the waters. However, there were no significant differences of 137Cs activity between the West Pacific and the north South China Sea, and ocean current changes had no effect on the 137Cs activity levels of the water bodies.展开更多
Radium-224 activities in the western Arctic Ocean were measured viaship-board ^(220)Rn emanation technique during the Second Chinese National Arctic Expedition. Theresults showed that the ^(224)Ra activities in the st...Radium-224 activities in the western Arctic Ocean were measured viaship-board ^(220)Rn emanation technique during the Second Chinese National Arctic Expedition. Theresults showed that the ^(224)Ra activities in the study areas ranged from being less than 0.08 to3.58 Bq/m^3, with an average of 0.23 Bq/m^3. The low ^(224)Ra concentration in the surface water wasattributed to the influence of sea ice melted water. The horizontal distribution of surface^(224)Ra in the western Arctic Ocean showed a high ^(224)Ra characteristics occurred along the slopearound 160°W, providing evidence for the importance of ice-rafted sediments to controlling thedistribution of radium isotopes in the Arctic Ocean. Mostly, ^(224)Ra concentrations increased withthe depth in the shelf region and reached a maximum at 75 m at the central Canada Basin, whichfurther confirms the importance of the transport of shelf bottom water to maintaining the upperhalocline layer in the Canada Basin.展开更多
本文介绍了测量海水中224Ra和223Ra比活度的国际通用仪器镭延迟符合计数器(Ra De CC),该仪器具有效率高、灵敏度高、背景值低、方便携带和适合海上现场测量等优点。结合本实验室3 a使用经验和工作数据,对仪器测量误差、探测效率、本底...本文介绍了测量海水中224Ra和223Ra比活度的国际通用仪器镭延迟符合计数器(Ra De CC),该仪器具有效率高、灵敏度高、背景值低、方便携带和适合海上现场测量等优点。结合本实验室3 a使用经验和工作数据,对仪器测量误差、探测效率、本底值和探测限等做出系统的阐述和讨论。结果表明,Ra De CC对224Ra和223Ra的探测效率分别在0.47~0.59和0.45~0.57之间,探测限分别为0.04 dpm和0.01 dpm,对224Ra和223Ra测量的相对标准偏差一般在5%和15%左右,但是,当224Ra比活度低于5 dpm/100 L时,变异系数将升高至10%~30%;当223Ra低于0.3 dpm/100 L时,变异系数将高达20%~80%。展开更多
基金The Natural Science Foundation of Guangdong Province of China under contract No.2017A030310592the Open Project of State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences under contract No.LTO1709the Key Program of Bureau Director of State Oceanic Administration,P.R.China under contract No.180104
文摘This paper reports the distribution of natural radionuclides of 224, 223Ra in the surface water and stratified waters of the Luzon Strait and its adjacent waters during the cruises of September 2015 and May 2016. To understand the impact of the Fukushima nuclear accident, the artificial radionuclide 137Cs in the waters was also analyzed. The results showed that the activities of 224, 223Ra and 137Cs were all within the natural radioactive background levels of the marine environment in the South China Sea. 224Ra had a higher activity level in the water of the north South China Sea to the west of the Luzon Strait, and a lower activity level in the oceanic Philippine Sea to the east. The137Cs activity had no obvious spatial trends. Based on the vertical trends of 224Ra, 137Cs, and water temperature and salinity at three stations(LS3, LS5 and LS8), the distinct characteristics of the activity levels and gradients of224Ra and 137Cs among the tropical surface water, subsurface water and mid-deep water were revealed. Typhoon Rainbow event reversed the overall circulation of the Luzon Strait and its adjacent area. A huge amount of western Pacific water characterized by low 224Ra activities flooded into the South China Sea, reducing the activity level of224Ra in the waters. However, there were no significant differences of 137Cs activity between the West Pacific and the north South China Sea, and ocean current changes had no effect on the 137Cs activity levels of the water bodies.
基金supported by Program for New Century Excellent Talents in University of China under contract No.NCET-04-0593Chinese Second Arctic Expedition Foundation.
文摘Radium-224 activities in the western Arctic Ocean were measured viaship-board ^(220)Rn emanation technique during the Second Chinese National Arctic Expedition. Theresults showed that the ^(224)Ra activities in the study areas ranged from being less than 0.08 to3.58 Bq/m^3, with an average of 0.23 Bq/m^3. The low ^(224)Ra concentration in the surface water wasattributed to the influence of sea ice melted water. The horizontal distribution of surface^(224)Ra in the western Arctic Ocean showed a high ^(224)Ra characteristics occurred along the slopearound 160°W, providing evidence for the importance of ice-rafted sediments to controlling thedistribution of radium isotopes in the Arctic Ocean. Mostly, ^(224)Ra concentrations increased withthe depth in the shelf region and reached a maximum at 75 m at the central Canada Basin, whichfurther confirms the importance of the transport of shelf bottom water to maintaining the upperhalocline layer in the Canada Basin.
