A research team in Kinki University surveyed the riverbeds of the Edo and Tone rivers which run into the Tokyo bay to study the movement of the radioactive cesium originated from the Fukushima Daiichi nuclear power plant accident this April. They sampled the mud layer about 20cm below the riverbed from five different locations, and measured the amount of cesium.

The team learned that the radioactive cesium from the accident has been accumulating in much lower layer of riverbeds than the 5cm-below-surface layer. 

In the Edo river area about 15km from the estuary (the place river meets the ocean) where roughly 53,000 bq/㎡ of cesium was detected at the time of the accident, 56% of the cesium was accumulating in the lower layer of riverbed below the 5cm layer.

In other four locations of the Tone river, 47~78% of the cesium was also accumulating in the lower layers than the 5cm layers.

The monitoring of the radioactive cesium conducted by the environmental ministry in much of the Tohoku and the Kanto rivers since May 2011 is limited to the samples taken from the layers that are around 5cm below the surfaces of the riverbeds. Prof. Hideo Yamazaki of the Kinki Univ. research team says, "Typhoons can move the radioactive cesium in the 20cm-below-surface layers into the Tokyo bay rather easily. The government should quickly adjust the monitoring methods to more accurately measure the distribution of the cesium in riverbeds to predict the effect on fish in the Tokyo bay."

This is regarding the news that they found exceeding amount of radioactive materials found in the feed hay that had been fed to cows raised for meat in Asakawa town, Fukushima. Prof. Endo of Kyoto Medical University whose expertise is effects of radiation said, "In a case of 3,400 bq/kg (max) of cesium detected from beef distributed from Minami Soma city, they found 75,000 bq in the feed hay. It depends on the amount a cow had eaten, as well as the duration between feeding and beef distribution, it is possible that distributed beef may have contained more than national limit of radioactive cesium. A person, however, would normally only eat between 200 and 300 grams of beef at a time, thus I don't think it would affect one's health upon eating beef a few times. It's better not to worry too much. Meanwhile, the government need to implement a measure to prevent such meat from reaching the markets."