Japan Soil Measurements Surprisingly High

by Jocelyn Kaiser on 25 March 2011, 6:14 PM

Meanwhile, on Wednesday the Japanese science ministry began to report measurements of cesium-137 in upland soil around the plant. The levels are highest from two points northeast of the plant, ranging from 8690 becquerels/kilogram to a high of 163,000 Bq/kg measured on 20 March from a point in Iitate about 40 kilometers northwest of the Fukushima plant

...Assuming the radiation is no more than 2 centimeters deep, Chen calculates that 163,000 Bq/kg is roughly equivalent to 8 million Bq/m2

The highest cesium-137 levels in some villages near Chernobyl were 5 million Bq/m2.


...The soil measurements are more significant for evacuation purposes than radioactivity in the air, says nuclear engineer Shih-Yew Chen of Argonne National Laboratory in Illinois, because cesium dust stays underfoot while air is transient.

Levels of cesium-137 are also more important than soil readings of iodine-131, which is short-lived and more of a concern in milk and vegetables. "It's the cesium that would prompt an evacuation," says Chen.

[link to news.sciencemag.org]