(UPDATE) The Ministry's other release says the measurement in Fukushima was done in July, therefore no detection of iodine-131 or any other short-lived nuclides. The Ministry sat on the data for only 5 months then.
or 47 times as much as all the 45 prefectures (excluding Fukushima and Miyagi) combined.
Or 145 million times as much as the pre-accident annual number for Fukushima, in half a month.
It took only 9 months for the Ministry of Education and Science to finally disclose the number for Fukushima Prefecture. The Ministry is yet to say anything about Miyagi Prefecture.
The ostensible reason for not disclosing the numbers for Fukushima and Miyagi has been that the measuring stations got damaged by the earthquake. Well, by releasing the data, albeit very late, the Ministry makes it rather clear that the measuring station in Fukushima was just fine, and it had the data.
Still, the number is only for radioactive cesium (134 and 137). No word about radioactive iodine, or about any other nuclide.
From Asahi Shinbun (12/14/2011):
Regarding the radioactive cesium that has been released into the atmosphere as the result of the Fukushima I Nuclear Power Plant accident, the Ministry of Education and Science announced on December 14 that the cumulative amount of radioactive cesium fallout in 4 months after the accident in Fukushima Prefecture was 6.83 million becquerels/square meter. The Ministry announced the cumulative amounts of radioactive cesium fallout for the 45 prefectures last month, excluding Fukushima and Miyagi. The amount in Fukushima is 168 times as much as that in Ibaraki Prefecture (40,801 becquerels) which had the highest amount among the 45 prefectures, and 47 times as much as the amount for the 45 prefectures combined (144,446 becquerels).
The numbers are the cumulative numbers, measuring cesium-134 and cesium-137 from the dusts collected in containers at institutes of public health throughout Japan from March to June. The analysis for Fukushima Prefecture was delayed because of the March 11 earthquake/tsunami. The measuring location was in Okuma-machi where Fukushima I Nuclear Power Plant is located. Of the 6,836,050 becquerels that fell [between March and June], 94% fell during March, attesting to the severity of the situation right after the accident. There was nuclear fallout from the past atmospheric nuclear testing before the Fukushima accident, but the cumulative fallout for Fukushima for the year 2009 was 0.044 becquerel.
For the entire year of 2009, Fukushima had 0.044 becquerel of radioactive cesium fallout.
In March of 2011, it had over 6.4 million becquerels. That's 145 million times more than the pre-accident level for a year, in half a month.
The Ministry of Education and Science's press release on December 14 (Japanese only) simply states the reason for the disclosure now as "The results just came in", on top of page 2.
Aside from cesium-134 and cesium-137, the press release also states the numbers for tellurium-129, tellurium-129m, and cesium-136. For the 4 months period in Fukushima, they are:
tellurium-129: 528,936 becquerels/square meter
tellurium-129m: 2,042,500 becquerels/square meter
cesium-136: 247,000 becquerels/square meter (March only)
(The Ministry uses Mbecquerels/square kilometer.)
A smart move by the Ministry, I suppose, to disclose the worst number (in Fukushima) first before disclosing the number for Miyagi, which I suspect to be much higher than that of Ibaraki.