| 摘要: |
| 用HPGeγ谱分析方法测定了胶州湾表层沉积物中放射性核素含量。样品中40K、137Cs、210Pb、226Ra、228Ra、228Th和238U的平均含量分别为688, 3.28, 61.0, 26.5, 40.3, 44.8, 39.2Bq/kg；东部海区沉积物40K和137Cs含量比其余海区低, 但210Pb、226Ra、228Ra、228Th和238U比其他海区高；除湾东部样品中的210Pb、226Ra、228Ra、228Th和238U之外, 粒径小于0.063mm部分中的放射性核素含量高于粒径大于0.063mm部分。除东部海区外, 湾内其余海区表层沉积物中放射性核素含量和矿物组成基本一致, 说明东部海区的沉积物的物质来源与其余海区不同。胶州湾表层沉积物与流域土壤放射性核素含量水平一致, 所以胶州湾沉积物主要物源为流域陆源碎屑。表层沉积物中放射性核素含量与矿物组成具有相关性。铀和钍放射系衰变不平衡, 总体样品和粒径小于0.063mm部分, 铀系中210Pb相对于226Ra过剩, 226Ra相对于238U亏损, 228Th相对于228Ra过剩。
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| 关键词: 放射性核素,碎屑矿物,胶州湾 |
| DOI：10.11693/hyhz200305004004 |
| 分类号: |
| 基金项目:国家自然科学重点基金资助项目,40036010号 |
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| RADIONUCLIDES AND MINERALS IN SURFACE SEDIMENTS OF JIAOZHOU BAY |
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JIA Cheng-Xia1, LIU Guang-Shan1, XU Mao-Quan1, HUANG Yi-Pu1, ZHANG Jing2
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1.Department of Oceanography, Institute of Subtropical Oceanography Xiamen University;2.State Key Laboratory Of Estuarine and Coastal Research, East China Normal University
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| Abstract: |
| Radionuclides in the surface sediments collecting from Jiaozhou Bay have been measured with HPGe γspectrometry. The average contents of 40K, 137Cs, 210Pb, 226Ra, 228Ra, 228Th, 238U are 688, 3.28, 61.0, 26.5, 40.3, 44.8, 39.2Bq/kg. The contents of 40K and 137Cs in sediment of east bay are lower than other area but the contents of 210Pb, 226Ra, 228Ra, 228Th, 238U are higher than other area. The radionuclide contents in portion of size < 0.063mm is higher than that of size > 0.063mm except east bay where the contents of 210Pb, 226Ra, 228Ra, 228Th, 238U are out of the ordinary for size grade. The minerals in the surface sediments collecting from Jiaozhou Bay have also been studied. The minerals of size < 0.063mm are on 80.1%—90.3%. The major heavy and light minerals in the 0.063—0.125mm are epidote, amphibolite, metal mineral and quartz, orthoclase, plagioclase and nepheline. The results show that the composition ofminerals in east bay is obviously different from other area where the radionuclide content and mineralogical composition are no distinct different, suggesting that sediment sources of the east bay are different from other regions. Radionuclides contents in surface sediments of Jiaozhou Bay are consistent with those in the soil of drainage basin, which indicates that sediments of Jiaozhou Bay are mainly terrigenous. The radionuclide contents correlate with the mineralogical compositions. The geochemical behaviors of the radionuclides in sediment were discussed. Uranium and thorium series are in disequilibrium. Generally the portion of size grade > 0.063mm of sample 210Pb is excess to 226Ra, 226Ra is deficient to 238U, 228Th is excess to 228Ra.
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| Key words: Radioactive nuclides, Clastic mineral, Jiaozhou Bay |
