The Oceanographic Society of Japan on July 25 urged the government to more stringently analyze radioactivity in seawater to get a precise picture of the contamination from the Fukushima No. 1 nuclear power plant.
The Oceanographic Society of Japan on July 25 urged the government to more stringently analyze radioactivity in seawater to get a precise picture of the contamination from the Fukushima No. 1 nuclear power plant.
The Ministry of Education, Culture, Sports, Science and Technology, which is checking seawater in the Pacific Ocean off Miyagi, Fukushima and Ibaraki prefectures, has reported that many radioactive substances are "not detectable" at many sampling locations.
A proposal presented by the society said this lack of information is because the measurement method is not stringent enough.
For example, the detection threshold for cesium-137 is currently about 9 becquerels per liter, and any value below this limit is labeled "not detectable."
The oceanographers called for more highly sensitive analysis methods because even radioactivity on the order of a few becquerels per liter could accumulate in fish and shellfish, and thus the food chain.
"If fish and shellfish live long spans of time, they could come to contain several hundred becquerels of cesium per kilogram in their body tissues," the oceanographers warned.