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Emission of spherical cesium-bearing particles from an early stage of the Fukushima nuclear accident.

Adachi K, Kajino M, Zaizen Y, Igarashi Y - Sci Rep (2013)

Bottom Line: However, we still do not know the exact physical and chemical properties of the radioactive materials.In contrast to the Cs-bearing radioactive materials that are currently assumed, these particles are larger, contain Fe, Zn, and Cs, and are water insoluble.Our simulation indicates that the spherical Cs-bearing particles mainly fell onto the ground by dry deposition.

View Article: PubMed Central - PubMed

Affiliation: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, Japan. adachik@mrijma.go.jp

ABSTRACT
The Fukushima nuclear accident released radioactive materials into the environment over the entire Northern Hemisphere in March 2011, and the Japanese government is spending large amounts of money to clean up the contaminated residential areas and agricultural fields. However, we still do not know the exact physical and chemical properties of the radioactive materials. This study directly observed spherical Cs-bearing particles emitted during a relatively early stage (March 14-15) of the accident. In contrast to the Cs-bearing radioactive materials that are currently assumed, these particles are larger, contain Fe, Zn, and Cs, and are water insoluble. Our simulation indicates that the spherical Cs-bearing particles mainly fell onto the ground by dry deposition. The finding of the spherical Cs particles will be a key to understand the processes of the accident and to accurately evaluate the health impacts and the residence time in the environment.

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SEM and EDS mapping images of a radioactive Cs-bearing particle from the sample collected during March 14, 21:10 and March 15, 09:10.(a) A Cs-bearing particle partially embedded within a carbon paste. (b) The same Cs-bearing particle as a) but measured the next day. The particle shows a spherical shape. (c) An elemental mapping (Cs) of the particle (a). (d) The EDS spectrum of the particle a) (black line). The red line shows the spectrum from the glass substrate. The Cs in the particle shows multiple peaks. (e) An elemental mapping of the other elements within the area. O, Si, Cl, Mn, Fe, and Zn are possibly coexistent with Cs within the particle.
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f3: SEM and EDS mapping images of a radioactive Cs-bearing particle from the sample collected during March 14, 21:10 and March 15, 09:10.(a) A Cs-bearing particle partially embedded within a carbon paste. (b) The same Cs-bearing particle as a) but measured the next day. The particle shows a spherical shape. (c) An elemental mapping (Cs) of the particle (a). (d) The EDS spectrum of the particle a) (black line). The red line shows the spectrum from the glass substrate. The Cs in the particle shows multiple peaks. (e) An elemental mapping of the other elements within the area. O, Si, Cl, Mn, Fe, and Zn are possibly coexistent with Cs within the particle.

Mentions: In Figure 3, we show a particle containing Cs (Cs Particle 1). The particle is spherical with a diameter of 2.6 μm. The energy dispersive X-ray spectrometer (EDS) spectrum shows Cs peaks. The Cs distribution in the elemental mapping image indicates that the spherical particles consist of Cs along with substantial amounts of Fe and Zn and minor amounts of Cl, Mn, and O. The decay-corrected activity (as of March 2011) of Cs Particle 1 is 3.27 ± 0.04 and 3.31 ± 0.06 Bq for 137Cs and 134Cs, respectively (Fig. S5). Assuming a particle density of 2.0 g/cm3, the Cs mass percentage within the particle is estimated from its activity (Bq) to be 5.5. Another Cs-bearing particles (Cs particles 2 and 3) from the same filter but different spots are similar to Cs Particle 1, although they have weaker activity (Fig. S6). The particles consist of Fe, Zn, and Cs and are approximately 2.0 μm in diameter. The radioactivity for Cs particle 2 is 0.66 ± 0.02 and 0.78 ± 0.04 Bq for 137Cs and 134Cs, respectively. The Cs mass percentage within Particle 2 is estimated from its activity to be 2.5. Assuming that the entire the radioactivity in the Plume 1 was from the Cs-bearing spherical particles gives an average of 1.4 Bq per particle, which is comparable to that of Particle 2.


Emission of spherical cesium-bearing particles from an early stage of the Fukushima nuclear accident.

Adachi K, Kajino M, Zaizen Y, Igarashi Y - Sci Rep (2013)

SEM and EDS mapping images of a radioactive Cs-bearing particle from the sample collected during March 14, 21:10 and March 15, 09:10.(a) A Cs-bearing particle partially embedded within a carbon paste. (b) The same Cs-bearing particle as a) but measured the next day. The particle shows a spherical shape. (c) An elemental mapping (Cs) of the particle (a). (d) The EDS spectrum of the particle a) (black line). The red line shows the spectrum from the glass substrate. The Cs in the particle shows multiple peaks. (e) An elemental mapping of the other elements within the area. O, Si, Cl, Mn, Fe, and Zn are possibly coexistent with Cs within the particle.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3757362&req=5

f3: SEM and EDS mapping images of a radioactive Cs-bearing particle from the sample collected during March 14, 21:10 and March 15, 09:10.(a) A Cs-bearing particle partially embedded within a carbon paste. (b) The same Cs-bearing particle as a) but measured the next day. The particle shows a spherical shape. (c) An elemental mapping (Cs) of the particle (a). (d) The EDS spectrum of the particle a) (black line). The red line shows the spectrum from the glass substrate. The Cs in the particle shows multiple peaks. (e) An elemental mapping of the other elements within the area. O, Si, Cl, Mn, Fe, and Zn are possibly coexistent with Cs within the particle.
Mentions: In Figure 3, we show a particle containing Cs (Cs Particle 1). The particle is spherical with a diameter of 2.6 μm. The energy dispersive X-ray spectrometer (EDS) spectrum shows Cs peaks. The Cs distribution in the elemental mapping image indicates that the spherical particles consist of Cs along with substantial amounts of Fe and Zn and minor amounts of Cl, Mn, and O. The decay-corrected activity (as of March 2011) of Cs Particle 1 is 3.27 ± 0.04 and 3.31 ± 0.06 Bq for 137Cs and 134Cs, respectively (Fig. S5). Assuming a particle density of 2.0 g/cm3, the Cs mass percentage within the particle is estimated from its activity (Bq) to be 5.5. Another Cs-bearing particles (Cs particles 2 and 3) from the same filter but different spots are similar to Cs Particle 1, although they have weaker activity (Fig. S6). The particles consist of Fe, Zn, and Cs and are approximately 2.0 μm in diameter. The radioactivity for Cs particle 2 is 0.66 ± 0.02 and 0.78 ± 0.04 Bq for 137Cs and 134Cs, respectively. The Cs mass percentage within Particle 2 is estimated from its activity to be 2.5. Assuming that the entire the radioactivity in the Plume 1 was from the Cs-bearing spherical particles gives an average of 1.4 Bq per particle, which is comparable to that of Particle 2.

Bottom Line: However, we still do not know the exact physical and chemical properties of the radioactive materials.In contrast to the Cs-bearing radioactive materials that are currently assumed, these particles are larger, contain Fe, Zn, and Cs, and are water insoluble.Our simulation indicates that the spherical Cs-bearing particles mainly fell onto the ground by dry deposition.

View Article: PubMed Central - PubMed

Affiliation: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, Ibaraki, Japan. adachik@mrijma.go.jp

ABSTRACT
The Fukushima nuclear accident released radioactive materials into the environment over the entire Northern Hemisphere in March 2011, and the Japanese government is spending large amounts of money to clean up the contaminated residential areas and agricultural fields. However, we still do not know the exact physical and chemical properties of the radioactive materials. This study directly observed spherical Cs-bearing particles emitted during a relatively early stage (March 14-15) of the accident. In contrast to the Cs-bearing radioactive materials that are currently assumed, these particles are larger, contain Fe, Zn, and Cs, and are water insoluble. Our simulation indicates that the spherical Cs-bearing particles mainly fell onto the ground by dry deposition. The finding of the spherical Cs particles will be a key to understand the processes of the accident and to accurately evaluate the health impacts and the residence time in the environment.

Show MeSH
Related in: MedlinePlus