環境

This study investigated the radioactive cesium released from the Fukushima Daiichi Nuclear Power Station accident in the river water of the Tama River.

As a result, the value of Hinobashi was about 1.5 mBq / kg to 4 mBq / kg regardless of the sampling time.

Suspended radioactive Cs was always detected in river water samples of Hinohashi.

Trace elements analyzes of freeze-dried samples of river water were performed and compared with the survey results of the 1980s.

The results of the 2019 trace element survey showed that the values of most elements were several to 50 times lower than the results of 2019.

It turns out that the river water is clean.

We have developed a simple analytical method for β-ray emitting nuclides (90Sr).

It was found that there was no 90Sr contamination.

We have developed a method for analyzing isotopes of the natural radionuclides uranium and thorium in rivers.

Uranium was able to quantify 0.039 μg / L (0.49 mBq / L) and thorium 0.021 μg / L (0.12 mBq / L).

We have found that these values are considerably lower than the environmental standards.

Haruaki MATSUURA

Naoto HAGURA

Takafumi UCHIYAMA

Taiki MUTO

Yuko KIMOTO