TFWT and OBT Concentrations in Soybean Plants Exposed to HTO Vapor at Different Growth Stages

콩의 생육단계별 HTO 증기 피폭에 따른 작물체내 TFWT 및 OBT 농도

  • Lim, K.M. (Korea Atomic Energy Research Institute) ;
  • Choi, Y.H. (Korea Atomic Energy Research Institute) ;
  • Lee, W.Y. (Korea Atomic Energy Research Institute) ;
  • Park, H.G. (Korea Atomic Energy Research Institute) ;
  • Kang, H.S. (Korea Atomic Energy Research Institute) ;
  • Choi, H.J. (Korea Atomic Energy Research Institute) ;
  • Lee, H.S. (Korea Atomic Energy Research Institute)
  • Published : 2004.12.30

Abstract

Soybean plants were exposed to HTO vapor in an exposure box for 1 hour at different growth stages. Relative concentrations of TFWT at the end of exposure (percent ratios of TFWT concentrations to mean HTO concentrations in air moisture in the box during exposure) decreased on the whole in the order of leaf > shell > seed > stem with the highest values of 40.2% and 6.4% for leaf and stem, respectively. TFWT concentrations reduced by factors of several thousands to several hundred-thousands from the end of exposure till the harvest. The reduction factor decreased in the order of leaf > shell > seed > stem. Relative OBT concentrations at harvest (ratios of the OBT concentration in the dry plant part at harvest to the initial leaf TFWT concentration, ml $g^{-1}$) were in the range of $2.2{\times}10^{-5}{\sim}9.5{\times}10^{-3}$ for seeds being the highest when the exposure was performed at the actively seed-developing stage. The exposure time-dependent variation in the OBT concentration was much greater in seeds and shells than in leaves and stems. It was indicated that OBT would contribute to almost all the radiation dose due to the consumption of soybean seeds in most cases after an acute exposure of growing plants to HTO vapor. Present results are applicable to establishing and validating soybean $^3H$ models for an acute accidental release of HTO.

피폭상자 내에서 콩을 생육단계별로 1시간 동안 HTO 증기에 피폭시켰다. 피폭종료 직후 작물체내 TFWT의 상대농도(피폭 시간 동안 피폭상자내 공기 수분중 평균 HTO 농도에 대한 백분율)는 대체로 잎 > 깍지 > 종실 > 줄기의 순으로 잎에서는 최고 40.2%, 줄기에서는 최고 6.4%였다. TFWT 농도는 수확시 까지 피폭시기에 따라 수 천${\sim}$수 십만 배 감소하였으며 대체로 잎 > 깍지 > 종실 > 줄기의 순으로 감소 정도가 켰다. 수확시 OBT 상대농도(피폭종료 직후 잎의 TFWT 농도에 대한 건조시료 내 OBT 농도의 비, $m{\ell}g^{-1}$)는 콩 종실의 경우 피폭시기에 따라 $2.2{\times}10^{-5}{\sim}9.5{\times}10^{-3}$의 범위로 종실의 발육 최성기 피폭시 가장 높았다. OBT 농도의 피폭시기에 따른 변이는 종실과 꼬투리에서 경엽부에 비해 훨씬 컸다. 콩의 생육중 급성 피폭시 종실 소비에 따른 섭취피폭 선량은 대부분의 경우 거의 전적으로 OBT에 기인할 것으로 예상되었다. 본 연구결과는 HTO의 단기적 사고방출시 두류내 $^3H$ 농도 예측을 위한 모델 수립 및 검증에 활용될 수 있다.

Keywords

References

  1. J.A. Garland and L. C. Cox, The absorption of tritum gas by English soils, plants and the sea, Water, Air and Soil Pollution 14, 103-114(1980)
  2. S. Okada and N. Momoshima, Overview of tritium: characteristics, sources, and problems. Health Physics 65, 595-609(1993)
  3. M. Murata and H. Noguchi, Dose delivered by unit amount of tritium released into the environment, J. Nuc. Sci. Tech., 34, 176-184(1997)
  4. S. Diabate and S. Strack, Organically bound tritium. Health Physics 65, 698-712(1993)
  5. S. Diabate and S. Strack, Doses due to Tritium Releases by NET-Data Base and Relevant Parameters on Biological Tritium Behaviour. KfK 4713, Kernforschungszentrum Karlsruhe(1990)
  6. 최용호, 임광묵, 이원윤, 강희석, 최희주, 이한수, 실비아디아바테, 지그프리드슈트락, 벼의종실 발육에 따른 주간 및 야간 HTO 증기 피폭시 TFWT 및 OBT 농도, 대한방사선방어학회지 제28권 1호, 9-18(2003)
  7. ICRP, Age-Dependent Doses to Members of the Public from Intake of Radionuclides, ICRP Publication 56, Part 1, Oxford, Pergamon Press(1990)
  8. A. W. Phippes, G. M. Kendall, J. W. Stather and T. P. Fell, Committed Equivalent Organ Doses from Intakes of Radionuclides. Chilton, NRPB-R245. HMSO, London(1991)
  9. N. A. Higgins, TRIF-An intermediate approach to environmental tritium modelling. J. Environ. Radioactiovity, 36, 253-267(1997)
  10. Y. H. Choi, K. M. Lim, W. Y. Lee, S. Diabate and S. Strack, Tissue free water tritium and organically bound tritium in the rice plant acutely exposed to atmospheric HTO vapor under semi-outdoor conditions, J. of Environ. Radioactivity 58, 67-85(2002)