Another gem from the open-access magazine Scientific Reports. If you think the blue butterfly mutation was flaky, this one takes the cake.
The paper is about freshwater fish contamination after the Fukushima I Nuclear Power Plant accident, published on Scientific Reports on April 29, 2013.
The first problem is right off the bat, the authors. They belong to Shiga University Economics Department, assessing risks of various financial instruments including insurance.
Here's Mr. Toshiaki Mizuno's bio, and here's Mr. Hideya Kubo's (in Japanese).
Uh.. Economics? Finance?
Here's their paper's abstract:
Overview of active cesium contamination of freshwater fish in Fukushima and Eastern Japan
Toshiaki Mizuno & Hideya Kubo (The Center for Risk Research, Shiga University)
This paper focuses on an overview of radioactive cesium 137 (quasi-Cs137 included Cs134) contamination of freshwater fish in Fukushima and eastern Japan based on the data published by the Fisheries Agency of the Japanese Government in 2011. In the area north and west of the Fukushima Nuclear plant, freshwater fish have been highly contaminated. For example, the mean of active cesium (quasi-Cs137) contamination of Ayu (Plecoglossus altivelis) is 2,657 Bq/kg at Mano River, 20–40 km north-west from the plant. Bioaccumulation is observed in the Agano river basin in Aizu sub-region, 70–150 km west from the plant. The active cesium (quasi-Cs137) contamination of carnivorous Salmondae is around 2 times higher than herbivorous Ayu. The extent of active cesium (quasi-Cs137) contamination of Ayu is observed in the entire eastern Japan. The some level of the contamination is recognized even in Shizuoka prefecture, 400 km south-west from the plant.
Scary, isn't it? Based on the quasi-Cs137 numbers (as the Fisheries Agency in their haste to measure anything radioactive right after the accident did not separate Cs-134 and Cs-137) the researcher drew up this contour map:
Figure 3: The isogram map shows average active cesium (quasi-Cs137) contamination level of the Ayu (Plecoglossus) captured in between May and September 2011 on each prefectures in eastern Japan.
Below the map, there is this remark:
Each isogram center points are each prefecture's capital city. We created the map using the GIS software which is 'MANDARA for windows 2000/XP/VISTA/7 Version 9.35' (the software copyright: 1992–2011 Tani Kenji).
I don't understand what they want to say in the first sentence.
This contour map, when it was first reported in Japan in April this year, spread fast, as the evidence of wide-area contamination of freshwater fish. "Look, even all of Shizuoka Prefecture is so contaminated!" It spread with comments like "The paper has been accepted by Nature Magazine! Peer-reviewed and authoritative!"
It turns out the economics researchers painted entire Shizuoka in green (0 to 10 Bq/kg of quasi-Cs137) from two samples that tested 5 Bq/kg and 2 Bq/kg.
As outsiders (not even a biologist or radiation expert) they were over-eager in drawing a radiation contamination contour map from a scant, incomplete data by the Fisheries Agency in the early days of the accident in 2011, while more detailed 2012 data was already available.
The original data points of the Fisheries Agency that these researchers used are plotted in this map (by @Kontan_Bigcat):
より大きな地図で アユのセシウムの放射能濃度（2011年） Radioactive cesium activity concentration in ayu after Fukushima nuclear disaster (2011) を表示
In the paper, part of which reads more like a tour guide, the two economists openly admits their data is not sufficient and over-estimating Cs-134 but at the same time declares the contamination has spread wide and all water systems are in danger:
The Japanese freshwater system is very high density as developed rice water paddy field, irrigation canal, urban water-system network. Therefore, we have to think that the contamination of freshwater fish is widespread not only in river basins but also all over the ground included all types of water-systems, for example, agricultural and urban water systems. The isogram map shows the contamination tendency quite well. The contamination levels of the freshwater fish provide insufficient data and the knowledge of the path about bioaccumulation. So, we will have to survey a more wide spread area and monitor bioaccumulation in each species level.
...Data 2011 of radioactive cesium of freshwater fish was analyzed by each local government according to the emergency food survey manual of radioactive substance14. The purpose of this manual is they avoid feeding high contaminated food it was defined by food security of emergency condition. Therefore, it is not aimed at collecting accurate data. As a result, this data did not distinguish between cesium137 and cesium134. Therefore, the analysis of this paper calculated by quasi-Cs137 included Cs134. They used germanium semiconductor machine when they measured the radioactive cesium contamination of freshwater fish. The measure time is from 10 minute to 1 hour. The calibration is only Cs137 in per week. The range of radioactive cesium applied only Cs137 regression equation. The result, when the case included Cs134 is relatively much, the numerical value become over estimation. The sample of freshwater fish was collected by each prefectural government by emergency policy of food security. In the survey, the fish sample collected 5–10 kg in one survey station. The measure is using wet condition fish. Ayu and small fish was measured hole body, while big fish measured the part of food portion.
I don't know who wrote English, but it is so bad that it makes my head spin. It could even be the Google translation. At least the blue butterfly paper was written in a decent enough English.
But no matter. Nature Japan decided to provide the very favorable Japanese translation of this hard-to-comprehend paper's abstract, and tweeted the page. So it is being tweeted again among people I follow.
I guess these two financial analysts just wanted to create a contour map like Professor Yukio Hayakawa, a volcanologist, did. If a volcanologist can, why not financial analysts?
At this point in time, after more than 2 years after the accident, people believe what they want to believe. Anything that shakes their belief system is either "pro-nuke" propaganda or "anti-radiation" over-reaction, depending on which "side" they are on. People in the "middle" who simply want to know what happened, what is happening, and what will happen are dwindling fast.