Fukushima contamination

Any gardener will tell you worms are responsible for the health of the soil.

High radioactive cesium levels detected in worms 20 km from nuke plant

Mainichi,

7 February, 2012

Radioactive cesium registering some 20,000 becquerels per kilogram has been found in worms 20 kilometers from the damaged Fukushima No. 1 nuclear plant.

The cesium was detected by a team including Motohiro Hasegawa, chief researcher in soil zoology at Japan's Forestry and Forest Products Research Institute. Worms are a source of food for many wild animals, and it is feared that radiation could gradually accumulate in the bodies of animals throughout the food chain.

The research team's findings will be announced at a meeting of the Ecological Society of Japan, to commence in the Shiga Prefecture city of Otsu on March 17.

Researchers dug up between 40 and 100 worms in national forests in the Fukushima Prefecture village of Kawauchi, which lies partly in the exclusion zone around the nuclear plant; the village of Otama, located 60 kilometers from the plant; and the town of Tadami, about 150 kilometers from the plant, between late August and late September last year.

The worms in Kawauchi registered 20,000 becquerels per kilogram of radiation. In Otama the level was around 1,000 becquerels per kilogram, while in Tadami 290 becquerels per kilogram was recorded.

The airborne radiation dose in Kawauchi at the time of the investigation was 3.11 microsieverts per hour, while in Otama, it was 0.33 microsieverts per hour, and in Tadami it was 0.12 microsieverts per hour. The figures show radioactive cesium concentration was greatest in the areas where airborne radiation dosage was highest.

In surveys conducted by the Forestry Agency between August and September last year, radioactivity of 1.38 million becquerels per square meter of soil was measured in Kawauchi, compared with between about 80,000 and 120,000 becquerels in Otama, and 20,000 becquerels in Tadami.

Much of the radioactive substances released from the plant in the nuclear disaster remains on fallen leaves. It is thought that worms have ingested the organic matter formed from the breakdown of these leaves.