Changes in Radioactivity Concentrations in Sea-bottom Soil
As a result of measuring dried sea-bottom soil samples collected in the coastal areas near Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi NPS, the concentrations of Cs-134 and Cs-137 were initially 1,000 Bq/kg but decreased in two years after the accident to 200 Bq/kg (down by 80%) and 500 Bq/kg (down by 50%), respectively. (Measuring Point T-1)
Radioactivity concentrations detected from sea-bottom soil samples collected 40 km offshore (Measuring Point M-C1) rose to 100 Bq/kg immediately after the accident but decreased to 10 Bq/kg a year later.
(Related to p.186 of Vol. 1, “Distribution of Radioactive Cesium in the Ocean”)
- Included in this reference material on March 31, 2014
- Updated on March 31, 2023