The Japan Agency for Marine-Earth Science and Technology (JAMSTEC), which only yesterday announced the cesium contamination of Pacific Ocean at 5000 meters deep, disclosed the result of their simulation of dispersion of radioactive cesium on the surface of Pacific Ocean.
Now they tell us that the contaminated water from the Fukushima I Nuclear Power Plant accident may have reached the international date line in 4 to 5 months after the accident.
That would be in July-August time frame.
The map is cut off right at the international date line, as if that's all the researchers cared about. (After all, they are the government researchers at this government Agency.) But rest assured as the researchers and the reporters all say there will be no effect on health. (Whose health?)
From Asahi Shinbun (11/21/2011):
The water contaminated with radioactive materials from the Fukushima I Nuclear Power Plant has spread to the international date line, about 4000 kilomters east of Japan -- that is the simulation result announced by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) announced. The simulation uses cesium-137 density. It is less than one-2000th of the safety standard for drinking water [200 becquerels/liter, post-Fukushima], but it is more than 10 times as much as that before the accident.
The researchers at JAMSTEC led by Y. Masumoto used the densities of radioactive materials measured in the ocean near Fukushima I Nuclear Power Plant to simulate the dispersion considering various factors including ocean convection.
Highly contaminated water leaked from the pit near the water intake canal at Fukushima I Nuke Plant after the accident. According to the simulation, the contaminated water first spread along the coast, and gradually spread offshore. It was further dispersed in the complex movement of the Kuroshio (Japan) Current and the Oyashio (Kurile) Current, and it reached the international date line in 4 to 5 months after the accident [, according to the simulation].
The researchers say there would not have been much difference in dispersion if they had assumed the radioactive materials dispersed in the atmosphere had fallen on the ocean.
As of the end of November, the density of radioactive cesium-137 would be 0.1 to 0.01 becquerel per liter, or one-2000th to one-20000th of the standard for drinking water that the Ministry of Health set.
The survey by the Ministry of Education shows several becquerels per liter of radioactive cesium in the sea water near Fukushima I Nuke Plant. The numbers [from the JAMSTEC simulation] are lower, but they are still 10 to 100 times as much as the pre-accident levels. Effects on marine life should be monitored carefully.
What does the drinking water standard for humans have to do with the cesium-137 density in the middle of Pacific Ocean? (What about for plankton and fish?)
Yomiuri Shinbun has the numbers much higher than Asahi. The paper says there are locations with 1 to 5 becquerels/liter cesium-137 in the simulation, though most fall between 0.01 to 0.5 becquerels/liter. That's 10 (0.01 becquerel/liter locations) to 5000 (in 5 becquerels/liter locations) times the pre-accident, as Yomiuri says the pre-accident level is 0.001 becquerel/liter.
Ah. The reporters... I'm looking for this particular paper, but so far unsuccessful.