1028 aoyama
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1028 aoyama

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1028 aoyama 1028 aoyama Presentation Transcript

  • Fukushima derived radionuclides in the ocean Michio Aoyama Meteorological Research Institute, Japan Talk Outline 1. Global cesium distribution and mass balance - pre Fukushima 2. Fukushima cesium - mass balance of 137Cs - surface transport and subduction to the ocean interior IAEA Scientific Forum 17-18 September 2013 Vienna, Austria
  • Decay corrected accumulative fallout of 137Cs derived from atmospheric weapons tests as of 1970 Michio Aoyama, Katsumi Hirose and Yasuhito Igarashi, Re- construction and updating our understanding on the global weapons tests 137Cs fallout, Journal of Environmental Monitoring, 8, 431-438, 2006. In Northern Hemisphere 765±79 PBq 1970 In the North Pacific Ocean 290±30 PBq 1970 69±7 PBq 2011 Chernobyl accident 1986 85 PBq
  • A pathway of weapons tests derived 137Cs in the North Pacific Ocean, tracer of sea water movement Fig. S2 Possible pathway of 137Cs in the Pacific Ocean based on 3-D observations of 137Cs in 2000s (Aoyama et al., 2013) We can expect that Fukushima origin radiocaesium should go same pathway View slide
  • Pathways of Fukushima derived radionuclides to the Ocean • Atmospheric deposition • Direct release • Groundwater discharge • River runoff TEPCO Press release 137Cs : 1.8E+12 Bq/m3 Simulated atmospheric deposition of 137Cs (Bq m-2) (by Masingar II of MRI) (Aoyama et al., in preparation) 4 View slide
  • Boiling Water Reactor Systems "Nuclear Reactor Concepts" Workshop Manual, U.S. NRC 3.6±0.7 PBq to the ocean (Tsumune et al., 2013) 14–17 PBq to the atmosphere 700 PBq was in the three core 140 PBq in stagnant water (Nishihara et al.,, 2011) (Nishihara et al., 2011) 140 PBq in stagnant water 12 - 15 PBq to the ocean 137Cs mass balance
  • More than 99% of released radioaesium to the ocean was transported offshore, then to the ocean interior 30 GBq day-1 Revised estimation
  • R/V Mirai NYK AQUARIUS 凌風丸 R/V Hakuho Maru NYK Heijin Sampling locations during the period from March 2011 to Oct. 2012
  • 10 Bq m-3 Aoyama, M. et al., Biogeosciences, 10, 3067-3078, 2013. 10 Bq m-3 Aoyama, M. et al., Biogeosciences, 10, 3067-3078, 2013. 134Cs in surface water in Oct. – Dec. 2011 134Cs in surface water in Jan. – Mar. 2012 (Aoyama et al., BG 10 3067-3078, 2013) Apr-Jun 2011 Jul-Sep 2011 Oct-Dec 2011 Jan-Mar 2012 Surface speed of contaminated water ca. 7 km day-1 8 X
  • 0 5 10 15 20 250 100 200 300 400 500 600 700 800 at 40N, 165E on 12 Oct. 2011 Stn KS1109-3101 and at 39N, 165E on 11 June 2012 stn RF1205-4418 KS1109-3101 RF1205-4418 134 Cs / Bq m -3 Depth/m Oxygen maximum Sigma0=26.3 Station 3101 4418 Year 2011 2012 Month 10 6 Bq m -2 Bq m -2 134Cs inventory 2710+-210 2350+-190 0 - 200 m 2150 520 Deeper than 200 m 520 1830 Oct. 2011 Over time, Cs moves east and subducted in the ocean interior June 2012
  • Bq m-3 137Cs cross section along 165 ºE in June 2012 Start of travel into ocean interior N
  • Possible pathway of Fukushima derived radionuclides in the North Pacific Ocean Fig. S2 Possible pathway of 137Cs in the Pacific Ocean We found start of travel of Fukushima derived radioactivity in the ocean interior.
  • Summary of budget of 137Cs for pre- and after the Fukushima accident Main portion of Fukushima derived radioactivity already subducted into the ocean interior and is moving to southwest ward.