Seasonal Variation of $^7Be$ and $^{137}Cs$ Concentrations in Airborne Dust, Dry Fallout and Precipitation in Daejeon

대전지역 대기부유진, 낙진 및 강수 중 $^7Be$$^{137}Cs$ 방사능 농도의 계절별 변화

  • Published : 2002.03.30

Abstract

The seasonal variation of $^7Be$ and $^{137}Cs$ concentrations in airborne dust, precipitation and dry fallout collected at Daejeon during the period of 1998 - 1999 has been studied. The annual mean values of 7Be concentrations in airborne dust, precipitation and dry fallout were in the range of $3.80{\sim}4.29\;mBq\;m^{-3},\;1.25{\sim}1.67\;Bq\;l^{-1},\;19.7{\sim}22.3 MBq\;km^{-2}$, respectively. The annual mean values of $^{137}Cs$ concentrations in airborne dust, precipitation and dry fallout ranged $1.08{\sim}1.28{\mu}Bq\;m^{-3},\;0.44{\sim}2.66 mBq\;l^{-1}\;\;0.036{\sim}0.0455\;MBq\;km^{-2}$, respectively. While the concentrations of $^7Be$ and $^{137}Cs$ in airborne dust and dry fallout were relatively higher in the spring and autumn when the amount of dry fallout increased than in other season, their concentrations in precipitation were relatively lower in the summer when the rainfall increased. The total depositions of $^7Be$ and $^{137}Cs$ due to dry fallout and precipitation were in the range of $80.7{\sim}137MBq\;km^{-2}$ and $0.059{\sim}0.060MBq\;km^{-2}$, respectively. More than 80% of $^7Be$ deposition resulted from precipitation, whereas about 60% of $^{137}Cs$ deposition was due to dry fallout.

References

  1. D. Lal and B. Peters, 'Cosmic ray produced radioactivity on the earth' in: Handbuch der Physik, XLVI/2, pp. 551, Springer-Verlag, Berlin (1967)
  2. D. Lal and H.E. Suess, 'The radioactivity of the atmosphere and hydrosphere', Ann. Rev. Nucl. Sci., 18, 407(1968) https://doi.org/10.1146/annurev.ns.18.120168.002203
  3. Natural background radiation in the United States, National Council on Radiation Protection Report, No. 45, Washington (1975)
  4. H. Amano and A. Kasai, 'Concentration of 7Be in the lower atmospheric and fallout rate in Tokai', Hokenbutsuri, 16, 99-103 (1981, Japanese)
  5. D. Lal, On the investigations of geophysicsical processes using cosmic ray produced radioactivity, in: Earth Science. Meteoritics, pp, 115-142, North- Holland Publishing Company, Amsterdam(1963)
  6. M.A. Krits, S.W. Rosner, E.F. Danielsen and H.B. Selkirk, 'Air mass origins and troposphere-to-stratosphere exchange associated with mid-latitude cyclogenesis and tropopause folding inferred from $^{7}$Be measurement', J. Geophys. Res. 96, 17405-17414 (1991)
  7. W. Viezee and H.B. Singh, 'The distribution f beryllium-7 in the troposphere' Implications n stratospheric/tropospheric air exchange, Gophys. Res. Letts., 7(10), 805-808 (1980)
  8. R.A. Brost, J. Feichter and M. Heimann, 'Three-dimensional simulation of $^{7}$Be in a global climate model', J. Geophys. Res. 96, 22423-22445 (1991) https://doi.org/10.1029/91JD02283
  9. Y. Ishikawa, H. Murakami, T. Sekine and K. Yoshihara, 'Precipitation scavenging studies of radionuclides in air using cosmogenic $^{7}$Be', J. Environ. Radioactivity, 26. 19-36 (1995)
  10. Y. Igarashi, M. Otsuji-Hatori and K. Hirose, 'Recent Deposition of $^{90}$Sr and $^{137}$Cs observed in Tsukuba, J. Environ. Radioactivity, 31(2), 157-169 (1996)
  11. Y. Igarashi, M. Aoyama, T. Miyano, K. Hirose and M. Tomita, 'Ahomalous $^{90}$Sr deposition during the fall, 1995 at MRI, Tsukuba, Japan, J. Radioanal. Nucl. Chem., 239(3), 539-542 (1999)
  12. Y. Igarashi, K. Hirose and M. Otsuji-hatori, 'Beryllium-7 deposition and its relation to sulfate deposition', J. Atmos. Chem., 29, 217-231 (1998) https://doi.org/10.1023/A:1005921113496
  13. Radioactivity survey data in Japan, National Institute of Radiological Sciences Report, ISSN 0441-2516, NIRS-RSD-128 (2000)