Ibaraki prefecture published the radiation survey result on 2/16/2012.
The survey was conducted from 8/4/2011 ~ 10/26/2011.
As the result, Strontium89 and Plutonium238 were under detectable level, Ibaraki prefecture asserted Fukushima did not affect Ibaraki.
However, they manipulated the “detectable level”. It’s turned out by telephone interview to Ibaraki prefecture. The person who confirmed this also took the sample of this article ..Breaking news : 8400 Bq/Kg of lead-210 was measured from sample of Yokohama
【重要】昨日発表された茨城県のストロンチウムとプルトニウムの調査について茨城県に確認した。 定量下限値は以下の通り Sr90：40Bq/m2 Sr89：300Bq/m2 Pu238：0.5Bq/m2 Pu239+240：0.5Bq/kg やっぱり300ですか そりゃ出ないわ・・Source
About the measurement of strontium and plutonium by Ibaraki prefecture, I confirmed the lowest detectable level with them. Here are the minimum amount to detect.
Strontium90 : 40Bq/m2
Strontium89 : 300Bq/m2
Plutonium238 : 0.5Bq/m2
Plutonium239+240 : 0.5Bq/kg
The half life time of strontium89 is only 50.52 days. Measurement of this nuclide is crucial to know if it’s from Fukushima. However, the detectable amount of strontium 89 is set extremely high, which can’t even be compared to the amount of strontium90.
Also, the half life time of Plutonium238 is 87.7 years, which is short compared to plutonium 239 and 240. Knowing the ratio of plutonium 238 and plutonium239+240 is important to see if it’s affected by Fukushima. However, their minimum detectable amounts are Bq/m2 and Bq/Kg, which can’t be compared either.