Dealing with the fallout in Fukushima – Part 2

On March 11, 2011, Japan experienced the unprecedented Tohoku earthquake. It was the largest in Japan’s history, and created a massive tsunami that impacted Japan’s northeastern coast. A result of the earthquake and tsunami was the meltdown of the Fukushima Daiichi Nuclear Power Plant. This meltdown had immediate and long-term impacts on the area. The March 1, 2019 Soils Matter blog covered those impacts. This blog will discuss current research by Japanese and American scientists to help solve some of the problems caused by the contamination in Fukushima soils.

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Research projects being conducted in the areas of Japan that have been impacted by the meltdown of the Fukushima Daiichi Nuclear Power Plant are focused on two main issues affecting the region.

  1. Contamination of soil by radioactive cesium (radiocesium), the health effects caused by this contamination, and the difficulty in removing it from the soil.
  2. Impact on the local farmers’ livelihoods caused by their inability to grow and/or sell their crops.

Kennesaw State University, USA

My research into the soil contamination in Iitate (Ee-tah-tay) Village seeks to find a way to chemically extract the radiocesium from the soil. Doing so would allow the soil to be re-used, or at the very least, disposed of more easily. Knowing something about the soils in this area is important.

Student working in lab with soil samples.
James Thornhill, from Ferreira’s lab, treats clay from Fukushima soil. Courtesy Dan Ferreira.

Soils in Iitate Village are high in clay, particularly vermiculite clay. Vermiculite is a naturally-occurring mineral, which you might be familiar with as a common ingredient in some “potting soils.” When the radiocesium was deposited on the surface of these soils, it quickly bound to minerals like vermiculite. This made the radiocesium difficult to remove.

Looking back to your high school chemistry classes, you’ll recall that chemists classify elements in the Periodic Table. Elements are organized by their atomic number and other properties. Potassium and cesium are both in the same class of element. So, knowing something about how potassium acts with vermiculite might give us clues about cesium. (Since aluminum isn’t radioactive, it’s safer to research than cesium). Research on the behavior of potassium has shown that its removal from vermiculite is impossible once the two have interacted.  My lab developed a method that has shown some early promise at being able to remove radiocesium from contaminated Fukushima soil. While this research is still very preliminary, I hope that it will someday provide a solution for the Japanese government on what to do with the soil currently stockpiled in Iitate Village.

University of Tokyo, Japan

Farmer driving tractor to churn up saturated soils.
Farmer Kinichi Ookubos’ field is flooded and then churned as part of a remediation research project. The water is drained – taking much of the radiocesium with it – to nearby holding fields. Courtesy of Dan Ferreira.

Masaru Mizoguchi is working on another way to reduce the amount of radiocesium in farmers’ fields and crops. The high clay content could be a key to a solution. Clay particles are the smallest of soil particles (sand, silt and clay). When you mix soil and water, the clay stays suspended in the water column for a long time. Mizoguchi’s team flooded one farmer’s field and then churned the soil mechanically. After letting the sand and silt settle out, the water with the suspended clay was drained from the field into a retention pond. By removing some of the contaminated clay from the soil, the impact of that contamination on the rice grown in the field can be minimized.

Meiji University, Japan

As we reviewed in Part 1 of this series, many farmers had their topsoil removed as part of the cleanup efforts. The topsoil was replaced with poor soil, with few nutrients. Nutrient-rich topsoil is crucial to good yields, and nutritious crops. Kosuke Noborio is trying to help farmers grow their crops successfully in farm fields that have had their topsoil removed and replaced.

One way that Noborio is trying to help solve this problem is using fertigation. Just like it sounds, fertigation is the combination of irrigation and fertilization. Sensors in the soil measure factors like the soil’s moisture level and the concentration of nutrients in the soil. Then, a computer calculates how much water and nutrients are needed to maintain the soil at an optimal condition to support the growth of the plant. Fertigation systems automatically mix the right amounts of fertilizer with irrigation water. This supplies a constant stream of water and nutrients to the soil based on the plants’ needs. If this research is successful, it could provide evidence for farmers to use in applications for government grants to install these expensive systems on a larger scale.

Tokyo University of Agriculture, Japan

Some farmers in this region are struggling to sell their crops. People are nervous about eating food grown in Fukushima soil, despite the fact that laboratory tests of the food show that it is safe. Some farmers are growing non-food crops such as flowers or tobacco. Toru Nakajima wants to provide another alternative for farmers: energy crops. He conducted a research project studying the suitability of Fukushima soil for growing crops such as corn or Miscanthus. Both can also be used to make bioenergy (e.g. ethanol, methane, etc). The hope is that because these crops are not consumed, farmers might be able to sell them more easily and at a higher profit margin than other non-food crop alternatives.

Bright green Miscanthus grass with blue sky behind.
Miscanthus could be an alternative source of revenue – and energy – for Japanese farmers affected by the tragedy at Fukushima Daiichi Nuclear Power Plant. Credit: Bob Nichols, USDA.

Many scientists are working hard to try to help the people of Iitate Village rebuild their lives after the meltdown of the FDNPP. Aiding in these efforts is Resurrection of Fukushima, a non-profit organization of which Dr. Mizoguchi is a vice president. They coordinate projects in the region and assist scientists as much as possible to facilitate their research. Working together, hopefully we can help the famers of Iitate Village to rebuild their lives and recover from this devastating accident.

By Dan Ferreira, Kennesaw State University

Click here to read part 1 of this blog.

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