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Friday, October 21, 2011

Japanese Farming Will Survive Radiation Fallout

Just in case you forgot, back on March 11, 2011, Japan endured a Magnitude 9.0 earthquake that spawned a - depending on whom you talk to - a 60-foot tsunami wave that smacked the northeast coast of Japan. It also took out power to the Dai-ichi nuclear power generating facility in Fukushima-ken (Fukushima Prefecture) causing it to go into near-meltdown but spewing radiative materials into the air, water and surrounding soil for days, if not weeks.

As such, people did have some valid concerns that farming in that sector of Japan would have to be shut down for years until it could be decontaminated.

However, recent studies looking at how the radiation in Japan has accumulated in plants and soil notes that there is no long-term threat and that farmers can get back to work (Ed. Note: even if it is October and harvest time?).

On April 22 (a month later) after the radiation had begun spewing, Japan's government had evacuated a 30-kilometer swatch of area surrounding the Dai-ichi nuclear facility privately-owned by Tokyo Electric Power Company (TEPCO). They then imposed agricultural product restrictions.

On October 1, 2011, Japan lifted it's evacuation advisory in certain areas within a 20- to 30-kilometer radius from the shut-down nuclear plant (though it is still considered 'hot'). The effected areas include the towns of Hirono and Naraha, the village of Kawauchi, and parts of Minamisomo and Tamura, all located in Fukushima-ken. At the time, over 60,000 had forced to leave the area.

Even now, however, people are concerned about going back to recreate a normal life there because Japan's government has yet to reveal a proper strategy for dealing with the areas contaminated by radiation.

People are panicking because there are no data," says plant radiophysiology expert Nakanishi Tomoko (surname first) at the University of Tokyo.

Nakanishi is the coordinator of seven teams studying the impact of the disaster on soil, plants, animals, fisheries and forests for the next decade by measuring contamination levels and assessing the long-term threat. Early results - appearing in Radioisotopes, a Japanese journal, say things are looking good for farmers.

Her teams studied crops at a Tokyo research field, including cabbages and potatoes that were planted a few weeks after rains showered the field with radioisotopes from the reactors in Fukushima.

These plants crops were harvested weeks later on May 16, 2011 and were examined, with findings of low levels of radiation—around 9-becquerels per kilogram (Bq kg–1 wet weight), much lower than the 500Bq kg–1 safety limit for human consumption.

It was also determined that since most of the had accumulated on the plant leaves, it could be washed off - meaning the plants were not absorbing dangerous levels of radioisotopes directly from the soil.

Even looking at the more highly exposed fields around Fukushima, Nakanishi's crew found similar results, finding that most of the radiation in the plants accumulated on their surfaces.

Wheat leaves that were open at the time of the greatest fallout were heavily contaminated, with combined levels of Cesium-134 and Cesium-137 ranging from thousands to about 1-million Bq kg–1.

But, the study shows, leaves that unfolded after the fallout were largely free of contamination. Wheat ears from these plants contained 300–500 Bq kg–1 — within the prescribed radiation limit.

"It's harvest time now and farmers are wondering what to do," offers Nakanishi. "They can throw the current harvest away. But it is okay to plant again."

Despite this good news, the team's data also show that the radioisotopes seem to be stuck firmly to the soil, mainly in the top five centimeters, and are not being washed away by rain. This might prevent the radioisotopes from entering groundwater, but suggests that cleaning up the more radioactive public spaces in Fukushima-ken will not be easy.

IMPORTANT: A separate group from Kobe University, led by radiation expert Yamauchi Tomoya, has found that soil radiation levels at four sites in Fukushima-shi (Fukushima City), some 60 kilometers from the reactors, measured up to 47,000 Bq kg–1, surpassing the 10,000 Bq kg–1 human exposure safety level set by the government. Yamauchi says that these areas, which are outside the current 30-kilometer evacuation zone, should be evacuated immediately.

In May, 2011, Japan's agriculture ministry showed off a ¥490-million (~Cdn/US$6-million) initiative to develop clean-up techniques, including removing contaminated soil.

However, results from these initiatives won't be known for many months, says Nakanishi, highlighting again that the lack of information for residents is damning.

Just how deep is the soil contamination in each area? That's what people need to know. As such, just to be sure, some local Fukushima schools have dug out the top 50 centimeters of soil... though even then they aren't positive.

Still, take a look at the graph above... according to that, only a few centimeters of soil are holding the contamination. But... that's just from where they took the samples. What about the Kobe research? Why did they get radioactive sampling well above what Nakanishi's crew did? Were these studies done at the same approximate time?

But, guess what the schools are doing with the contaminated soil they have dug up? After digging it up, the dirt sits in the corners of the schools' property... big mounds of radioactive dirt.... free to blow into kids faces.

The agriculture ministry is also testing how well plants can clean the soil in highly contaminated areas, and several non-governmental organizations have followed suit with a campaign of sunflower planting, with the assumption being that these plants will absorb the radiation from the contaminated soil.

Nakanishi called this "nonsense", noting that this phyto­remediation can only absorb small amounts of radiation

However, Inoue Chihiro, an expert in soil and groundwater remediation at Tohoku University, offers that the phyto­remediation technique is worth examining, but warns that even if it works, there is still the problem of having to dispose of the radioactive plants.

Burying the soil is expensive, however. Inoue says that the cost of cleaning up a school playground could be ¥50 million (~Cdn/US 650,000), and there are more than 100 schools in the affected areas (for about a $65-million outlay of moolah!), not to mention parks and other public places.

As well, there is the additional costs of digging it up PLUS the fact that since Cesium-137 has a radioactive half-life of 30 years meaning it's 30 years to lose half it's radioactivity, and 30 years again to lose that new current half of radioactiviy, and so on), this stuff is going to be around for a long time. This means wherever the soil is buried/stored, it's going to have to be constantly monitored for weather exposure (and thus having it go down into the drinking water table).

By Andrew Joseph

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