These charts are made by one of people I follow on Twitter, Kontan_Bigcat, who seems to have been very meticulously following the published data (both official and private, like NPOs) on radioactivity in Japan and been producing excellent charts visualizing the data.
From his updated togetter on radioactivity in bottom-dwelling fish in northern Japan on the Pacific Ocean side, charts and his comments (I added some English labels):
Halibut, north of Miyagi (Miyagi, Iwate, Aomori, Hokkaido), up to 9/30/2012 data: 20 to 40 Bq/kg in Sendai Bay (Miyagi), no discernible downtrend in radioactivity. Aomori is seeing an increase, from 5 Bq/kg at most in spring but 20 Bq/kg since summer:
Halibut, outside the 30-kilometer radius from Fukushima I Nuclear Power Plant, up to 9/30/2012 data: Fish exceeding 1,000 Bq/kg is no longer found, but there is no discernible downtrend in radioactivity:
Shinchi-machi is located just south of Miyagi, and Iwaki City is north of Ibaraki.
Halibut, inside the 30-kilometer radius from Fukushima I Nuclear Power Plant, up to 9/30/2012 data: Monitoring survey inside the 20-kilometer radius started in April, but there doesn't seem to be a difference between inside the 20-kilometer radius and between 20 and 30 kilometer radius. Fish that exceed 1,000 Bq/kg are no longer found, but there is no discernible downtrend in radioactivity:
Halibut, Ibaraki and south of Ibaraki (Chiba), up to 9/30/2012 data: It seems the radioactivity is slowly declining south of Ooarai, but north of Hitachinaka [i.e. closer to Fukushima] continues to show 10 to 40 Bq/kg, and there is no discernible downtrend.:
And the last chart for halibut, plotting all the data points, from north (Aomori, Hokkaido) to south (south of Choshi, Chiba):
Interestingly, the recent high for the radioactivity in halibut was found not inside the 20-kilometer radius from the plant, as one might expect, but outside, off Iwaki City, at 150 Bq/kg or so. The radioactivity in halibut caught in or off Sendai Bay is not far behind.
Kontan_Bigcat also has charts for marbled sole, common skete, greenling, Pacific cod, and Japanese sea bass (not the bottom-dwelling fish, but they feed on food on or near the ocean bottom). One greenling sample near the 20-kilometer radius from the plant tested 25,800 Bq/kg in August this year, as he notes, but successive tests at the location yielded radioactivity one order of magnitude lower (above 1,000 Bq/kg).
As Washington Post reports (quoting AP), Woods Hole researcher Ken Buesseler speculates in his article in Science magazine that steady radioactive cesium levels may indicate that cesium is being freshly supplied from the broken nuclear power plant.
It is possible, but there are other major and obvious sources of radioactive materials all along the coast of northern Japan: Rivers carrying radioactive sediments all the way from the mountains (where a lot of radioactive materials remain, un-"decontaminated"). Abukuma River in Fukushima alone carries 50 billion becquerels of radioactive cesium per day to the Pacific Ocean. The river runs through the contaminated middle third of Fukushima, and reaches Sendai Bay in Miyagi.
He also does not seem to consider "bioconcentration" much either - concentration of radioactive materials going up the food chain. For example, abalones in the seawater with 40bq/kg of radioactive cesium and the non-detectable level of radioactive silver (Ag-110m) were found with high concentration of both, particularly Ag-110m. Abalones eat seaweed.
Then there are coastal currents which shift bottom sands, which seems to be happening as evidenced by increasing radioactivity in halibut caught off Aomori/Hokkaido.
But Mr. Buesseler may have mentioned these in his article, which I do not have access to.
Just like many other stories in the past about Fukushima, his article, or the articles by the foreign media based on his article have been (re-)imported to Japan, and some Japanese are tweeting the same thing they have tweeted often before: "See, a foreign scientist is saying this, and the respected foreign media is reporting it! See how our own government and media lie and hide stuff! Fukushima I Nuke Plant is leaking!"
They do not read the fine print, that the Woods Hole researcher created his charts using the data from the Japanese government (and probably TEPCO, which is now part of the government), which has been available to anyone all along, and that it is his hypothesis that the plant continues to leak radioactive water.
But that's too much details for them, apparently.
30-Day free trial by following the link.
Tokyo Time
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7 comments:
Some trends may be the result of seasonal changes (fish migrating north during the summer, etc.) Time will tell.
To see changes in charts like this, though, your friend would have to add a single line with the average contamination detected for each moth or something. Otherwise the cloud with multiple results makes it difficult to see.
Since these results are for bottom feeders, however, and cesium is accumulating in hotspots along the coast, Cesium 134 decay would be the main factor.
Thank you for sharing this information. I'm not sure I understand your last point about the Japanese public's reaction, though. Isn't it the case that it was a foreign researcher who took the data and studied it, and foreign media who ran the story? The fact that the data was available from the government or TEPCO means little, if the Japanese researchers and reporters ignore it. Is it any wonder some people think the domestic academics and the media have been co-opted by the government and industry?
Mike, many are not even aware that the data is from the Japanese government, and the same data has been used by the Japanese researchers (both at academic institutions and lay people) and even reported by the media.
They adore and detest anything foreign, depending on the occasion. In this case, and any case regarding nuclear accident, it's the former.
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In that case, they will come in great numbers (or not) to show some hate (or support) to that Woods Hole institute guy and other people from various place of varying notoriety, at Todai on Nov. 14th: http://www.whoi.edu.tokyoevent
Chirashi is here: http://www.whoi.edu/fileserver.do?id=134724&pt=2&p=141249
With instant translation (really, that part is the most impressive of the colloquium, try to do it once and you'll understand) in english/japanese.
JA, thanks. Are you going? Boy, do I smell Hakuhodo or do I smell Hakuhodo? (Todai's partner)
Tokyo University totally lost credibility over the nuke accident, thanks to Professor Sekimura who downplayed the nuclear accident non-stop in the first 2 weeks of the accident on NHK TV at the government's behest.
So it's sponsored by the Japanese government. I remember Woods Hole research ship was the only ship officially allowed by the government to enter the ocean off Fukushima.
I've always found the concept of prestigious educational institutes to be ridiculous. Generalisation and association = simplification.
I was under the impression that the reactors are still spewing crap into the air and ocean. I'd imagine it's like water through a sieve. They aren't sealed up properly and we still don't know where the fuel is or anything.
It's hard to tell if there's fresh contamination when it takes such a long time for the radiation to go away and they're trying so hard to pretend everything's okay. I assumed the radiation level would either stay the same or increase.
Wow, one and a half curie per day from this little river!
It got a real sea polluter. Natural decontamination waste, though.
At least we know that the pollution now widens, and soon Japanese fish can be considered as radioactive generally.
And other fish - it's like Russian Roulette whether you get a fish that has been in Japanese waters.
Thank you EX-SKF for sharing the information!
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