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Issue 4, 2012
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Uranium oxide and other airborne particles deposited on cypress leaves close to a nuclear facility

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Abstract

Enhanced activity of actinides and some decay products has been reported for the leaves of cypress trees (Chamaecyparis nootkatensis) at the edge of the Malvési uranium-processing facility, southwestern France. The enhanced activity is due to the release of actinides via the smokestacks and from artificial ponds inside the facility. This study was conducted to characterize airborne particulate matter deposited on the leaf surfaces and to investigate whether or not radioactive particles may be identified. Air-dried leaf samples were examined by scanning electron microscopy, in combination with energy-dispersive X-ray spectrometry. The samples were scanned systematically in both secondary and backscattered electron modes. Particles ranging in size from <200 nm to ∼40 μm were found on most portions of the adaxial leaf surface, but they are especially abundant at the boundary between facial and lateral leaves. The majority of the analyzed particles could be attributed to five principal classes: carbonates, silicates, sulfates, oxides/hydroxides, and halides. In addition, other types of particles were found, including Fe alloys; scheelite-group phases; phosphates; sulfides; and fly ash spheres. Similar particles were also observed on the surface of a wheat sample used for comparison. Of special interest are U-rich particles, which were observed on the cypress leaves only and which were identified as U oxides, except for one particle, which was a U-oxide-fluoride. These U-rich particles were released into the atmosphere by the nuclear facility prior to their deposition on the leaf surfaces. As most of the U-rich particles are <2.5 μm across, they are respirable. Once inhaled, particles containing alpha-emitting isotopes represent a potentially long-term source of ionizing radiation inside the lungs and thus, pose a threat to the health of people living nearby.

Graphical abstract: Uranium oxide and other airborne particles deposited on cypress leaves close to a nuclear facility

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Publication details

The article was received on 14 Dec 2011, accepted on 08 Feb 2012 and first published on 15 Feb 2012


Article type: Paper
DOI: 10.1039/C2EM11000H
Citation: J. Environ. Monit., 2012,14, 1263-1273
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    Uranium oxide and other airborne particles deposited on cypress leaves close to a nuclear facility

    R. Gieré, R. Kaltenmeier and L. Pourcelot, J. Environ. Monit., 2012, 14, 1263
    DOI: 10.1039/C2EM11000H

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