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Fukushima Marine Environment Monitoring (1 April 2011, 14.30 UTC)


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Fukushima Marine Environment Monitoring (1 April 2011, 14.30 UTC)

  1. 1. Marine Environment Monitoring<br />Assessment of IAEA Environment Laboratories on Data provided by Japan<br />IAEA Environment Laboratories, Monaco<br />
  2. 2. General comments<br />The contamination of the marine environment has occurred both through atmospheric fallout or washout with precipitation, and through discharges of contaminated water into the sea <br />Japanese institutes continue to perform measurements in seawater at 30 m and 330 m off the discharge points of Dai-ichi NPP, as well at 10 km and 20 km off-shore and along a North-South transect situated 30 km off-shore<br />
  3. 3. Seawater sampling offshore Fukushima carried out by Japanese Authorities (23 - 30 March 2011) <br />Seawater sampling locations of Japanese Authorities<br />Transect about 30 km offshore, sample locations separated by 10 kilometres, surface seawater sampled<br />Additional sampling stations at 10 and 20 km offshore, for which both surface and bottom seawater are sampled<br />
  4. 4. General Comments <br />Higher levels are measured 30 m, 330 m and 10 km near-shore relative to those measured 30 km off-shore <br />Concentration data off-shore reported for the past week show a quite heterogeneous distribution, as expected, both on the surface and deep layers, with general decreasing time trend<br />It can be expected that, in the absence of additional releases, the levels measured at the stations 30 km off-shore will continue to decrease significantly by dilution into deeper layers and dispersion by ocean currents<br />
  5. 5. Bathymetry and main ocean currents <br />Credit: SIROCCO<br />Credit: NOAA<br />
  6. 6. I-131 concentrations in seawater at 10 - 30 km off-shore FukushimaData submitted by Japanese authorities<br />
  7. 7. Cs-137 concentrations in seawater at 10-30 km off-shoreData submitted by Japanese authorities<br />
  8. 8. Monitoring of the Marine environment <br /><ul><li>Comparison of Cs-137 seawater concentrations with historical data
  9. 9. 30 km offshore surface water concentrations were up to 3-4 orders of magnitude higher than the values measured in 2005
  10. 10. 330 m East of Fukushima Dai-ichi concentrations were up to 3 orders of magnitude higher than the values measured offshore, this showing the high dilution capacity of the marine environment</li></ul>1<br />106<br />103<br />102<br />101<br />108<br />104<br />105<br />107<br />1<br />106<br />103<br />102<br />101<br />108<br />104<br />105<br />107<br />Bq.m-3<br />Bq.m-3<br />[1 – 101]<br />[103– 104]<br />[105– 107]<br />Cs-137 Bq.m-3<br />April 2005<br />30 km<br />24, 27 March 2011<br />
  11. 11. I-131 and Cs-137concentrations in seawater at the common discharge point of Units 1-4Data submitted by Japanese authorities<br />
  12. 12. I-131 and Cs-137concentrations in seawater at the common discharge point of Units 5-6Data submitted by Japanese authorities<br />
  13. 13. Conclusions<br />Measurements of seawater are carried out by Japanese authorities since 23 March and data are reported to the IAEA for information and assessment.<br />I-131 and Cs-137 were detected with highest activity concentrations of about 80 Bq/L and 25 Bq/L in surface water, respectively, on 23 March. <br />Data reported for 30 March show generally lower values below 10 Bq/L for both I-131 and Cs-137. A higher value of 80 Bq/l was measured at the point situated 10 km offshore for I-131, while Cs-137 at this station remains low at 8 Bq/l.<br />
  14. 14. Conclusions<br />Levels at 30 m and 330 m from the discharge points showed increasing concentrations up to 130 000 Bq/L for I-131 and 32 000 Bq/L for Cs-137<br />Modelling of the dispersion of radionuclides was initiated by the SIROCCO group of the Observatoire Midi-Pyrenees, University of Toulouse, and first results indicating the general pattern of dispersion are available. The results show an initial transport into north-east direction and fast dispersion along the Kuroshio curent. <br />One marine expert from IAEA Environmental Laboratories, Monaco currently in Japan to review and advise on marine sampling and measurements <br />