I saw several tweets (like these) today that has links to articles, posts about detection of strontium and plutonium in the fly ashes before and during the test burning of the disaster debris from Iwate Prefecture in Sanjo City, Niigata Prefecture. The city also disclosed the strontium and plutonium measurement of wood chips and soil samples from Iwate. There are even those retweeting an English article based on the Sanjo City test result, as if that gives some legitimacy to the fact that plutonium has been found.
Yes indeed, strontium and plutonium (Pu239+240) have been found. What these articles and tweets do not mention is that the levels are well within the background; they are actually much lower than the background measured in the past.
21 months after the nuclear accident, there are still enough people who see these articles and posts and freak out, "Look, there is plutonium detected! See how bad the Fukushima accident has really been! They've been lying to us!"
I know I'm totally wasting my breath here, as people believe what they want to believe anyway. But first, the PDF file from Sanjo City:
Plutonium 239+240 in wood chips from Otsuchi, Iwate, 0.0019 Bq/kg.
Plutonium 239+240 in soil samples from Otsushi, Iwate, max 0.13 Bq/kg.
Here are tables created from the Japan Chemical Analysis Center database.
Plutonium 239+240 in soil in Iwate Prefecture, from 1999 to 2010: Highest in 2004 at 2.6 Bq/kg. 0.27 and 1.6Bq/kg in 2010.
Plutonium 239+240 in soil in Niigata Prefecture, from 1999 to 2010: Highest in 1999 at 0.45 Bq/kg. 0.15 and 0.22 Bq/kg in 2010.
Strontium 90 in soil in Iwate Prefecture, from 1987 to 2011 (grassland picked for comparison, as Pu measurement is mostly on grassland): Highest in 1987 at 20.35 Bq/kg, 6.5 and 7 Bq/kg in 2011.
Strontium 90 in soil in Niigata Prefecture, from 1963 to 2011, intermittent (grassland): Highest in 1964 at 49.284 Bq/kg. 0.46 and 0.58 Bq/kg in 2011.
If the fly ashes only measured 0.016 Bq/kg of plutonium 239+240, that's actually low, considering the incineration condenses the per-kilo radioactivity by 100 to 300 folds.
Someone else in Japan recently fabricated the story that Hawaiians are suing the Japanese government and TEPCO because uranium of Fukushima origin has been detected from the urine. That spread very quickly on Twitter among people who do not/can not read English. I found out that the original English article was about depleted uranium in the army base. This someone is one of the few in Japan who clearly get a kick out of spreading false information.
For people who do not read or understand English well, these pieces of information accumulate like scums clogging the sewer, with no means to clear it.
For people who are not that curious to ask questions like "What was the background before the Fukushima nuke accident?", I don't know what to do.