No new results from the marine monitoring stations 30 km off-shore were reported for 27 or 28 March. However, new analyses in seawater 330 m east to the discharges point of NPP Units 1 – 4 were made available for 27 March. These concentrations show a significant decrease from 74 000 Becquerel per litre of iodine-131, 12 000 Becquerel per litre of cesium-137, and 12 000 Becquerel per litre of cesium-134 on 26 March to 11 000 Becquerel per litre of iodine-131 and 1 900 Becquerel per litre of cesium-137 on 27 March.

Sea water samples were also collected daily at a location 30 m from the common discharge point for Units 5 – 6. These results also show an increase in the radionuclide concentrations on 26 March. The sea water samples collected on March 27 show as well a decrease of the radionuclide concentration.

It can be expected that the data will be quite variable in the near future depending on the discharge levels. In general, dilutions by ocean currents and into deeper waters as well decay of short lived radionuclides e.g. I-131 or I-132 will soon lead to lower values.

Marine Organisms- First analyses were reported in fish carried out by the National Research Institute of Fishery Research. 5 samples of fish were collected from the port of Choshi (Chiba prefecture) and 4 of 5 samples showed Cs-137 concentrations below limit of detection. In one sample Cs-137 was found with 3 Bq/kg (fresh weight) and it was reported that it was slightly above the limit of detection. This concentration is far below any concern for fish consumption.

It is still too early to draw conclusions for expected concentrations on marine food, because the situation may change rapidly, however, it is expected that the detected initial concentrations of seawater will soon drop to lower values by dilution and the levels in marine food will most likely not reach levels above given limits for consumption, (presuming that discharges of contaminated seawater from the reactor will not continue). It is not expected that fish or other marine food will be collected in a close area to the NPP Fukushima at the present situation. Some marine algae are known to accumulate in particular I-131 and Tc-99m. However, these values will soon be of no concern due to the short half-lives of the radionuclides mentioned.
activities, respectively. The results should just be taken as indication of the dilution capacity and transport route of sea water.