Fukushima Marine Environment Monitoring - 19 April 2011
Marine Environment Monitoring<br />Assessment of IAEA Environment Laboratories on Data from the Marine Environment provided by Japan<br />Update 19 April<br />IAEA Environment Laboratories, Monaco<br />
General comments<br /><ul><li>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
Authorised discharge of low level contaminated water (4 April)
TEPCO and MEXT are continuing to conduct programmes for sea water sampling and to perform measurements. </li></li></ul><li>New plan for environmental assessment announced by Japanese authorities<br />NISA directions to TEPCO: <br /> In order to better understand the potential long term effects of the discharge of radioactive material to the marine environment, on 15 April, NISA directed TEPCO to:<br />continue monitoring at current and additional sampling locations;<br />sample biota (e.g. fish, shellfish, etc.) from the vicinity of the NPS;<br />perform an environmental impact assessment;<br />present the results of these actions to the public.<br />IAEA Environment Laboratories in collaboration with the other IAEA Divisions are ready to assist and collaborate with Japan, if requested.<br />
Seawater sampling carried out by TEPCO<br /><ul><li>TEPCO is sampling four near- shore stations (TEPCO1-4)
Since 5th of April six points situated 15 km off-shore along a north-south transect (TEPCO 5-10)
Following a Directive from NISA, on 16 April TEPCO announced that they will increase the number of sampling points. Four points will be added at 3 km from the coast and two points at 8 km from the coast.</li></li></ul><li>Seawater sampling carried out by TEPCO<br /><ul><li>Since 9 April the levels of I-131 and Cs-137 at the sampling points TEPCO 5-10 are lower than those at the near-shore stations (below 0.5 kBq/l) with a decreasing trend
Since 9 April the levels of I-131 and Cs-137 at the sampling points TEPCO No. 1 – 4 are below 20 kBq/l with a decreasing trend</li></li></ul><li>Concentrations in sea water near discharge point of <br />TEPCO 1-4<br />
Concentrations in sea water further off-shore<br />about 15 km from the coast<br />
Seawater sampling carried out by Japanese Authorities MEXT <br /><ul><li>North-South transect about 30 km offshore, sample locations separated by 10 kilometres, surface seawater sampled
Additional sampling stations at 10 and 20 km offshore, for which both surface and bottom seawater are sampled (No. 9 and 10)
On 4th April MEXT added stations A and B north-west of the sampling point 1 after discussion with the IAEA Environment Laboratories, Monaco</li></ul>Map 1<br />
15th April showed that Cs-137 and I-131 were detected at MEXT 4, 6 and 8. The highest concentrations were recorded at MEXT 4 (below 200 Bq/l for Cs-137 and about 160 Bq/l for I-131). At MEXT 6 and 8 sampling locations both Cs-137 and I-131 were reported at levels below about 40 Bq/l.<br />The results reported on 19th April (sampling date 17th April) showed that at the stations MEXT 5, 7 and 9, Cs-137 and I-131 are below 90 Bq/l. <br />Both Cs-137 and I-131 are “not detectable” at MEXT A and B.<br />Seawater sampling carried out by Japanese Authorities MEXT <br />
Conclusions<br /><ul><li>The highest levels are still measured close to the coast, namely 30 m, 330 m and 10 km near-shore even though with a decreasing trend.
Concentration data from about 30 km off-shore show a generally decreasing temporal trend
It can be expected that, if no additional releases occur, 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</li></li></ul><li>Conclusions<br />One marine expert from IAEA Environmental Laboratories, Monaco has been in Japan to review and advise on marine sampling and measurements. He was on the research vessel R/V MIRAI for two days; he visited the laboratory in Tokai and met and briefed in Tokyo the responsibles of the Japan Agency for Marine-Earth Science and Technology (JAMESTEC), MEXT, MOE, MOFA. <br />
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