Leaching of technetium from foliage by simulated rain

Myttenaere, C.; Daoust, C.; Roucoux, P.

doi:10.1016/0098-8472(80)90235-x

Cited by 17 publications

(4 citation statements)

References 6 publications

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“…Less than 10% of the Tc in leaves or leaf litter was removed using ethanol, and somewhat more (17% to 29%) was removed by aqueous and acid extractions. This is a relatively large percentage compared with the percentage of insoluble forms previously found in corn leaves (40%, Garten et al 1986b), soybean leaves (38%, Roucoux 1980), and tomato leaves (16%, Myttenaere et al 1980). Most (66 to 7 1 %) of the Tc present in maple leaves or tree leaf litter was insoluble and extractable only by boiling NaOH.…”

Section: Chemical Fractionation Of Tc In Leaves Wood and Littermentioning

confidence: 76%

Technetium-99 Cycling in Maple Trees

Garten¹,

Lomax²

1989

Health Physics

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Prior field studies near an old radioactive waste disposal site at Oak Ridge, TN, indicated that following root uptake, metabolism by deciduous trees rendered 99Tc less biogeochemically mobile than expected, based on chemistry of the pertechnetate (TcO-4) anion. Subsequently, the form of technetium (Tc) in maple tree (Acer sp.) sap, leaves, wood and forest leaf litter was characterized using one or more of the following methods: dialysis, physical fractionation, chemical extraction, gel permeation chromatography, enzymatic extraction, or thin layer chromatography (TLC) on silica gel. Chromatography (Sephadex G-25) of TcO-4 incubated in vitro with tree sap showed it to behave similar to TcO-4 anion. When labeled wood and leaf tissues were processed using a tissue homogenizer, 15% and 40%, respectively, of the Tc was solubilized into phosphate buffer. Most (65% to 80%) of the solubilized Tc passing a 0.45-micron filter also passed through an ultrafiltration membrane with a nominal molecular weight cutoff of 10,000 atomic mass units (amu). A majority (72% to 80%) of the Tc in wood could be chemically removed by successive extractions with ethanol, water and weak mineral acid. These same extractants removed only 23% to 31% of the Tc from maple leaves or forest floor leaf litter. Most of the Tc in leaves and leaf litter was removed only by strongly alkaline reagents typically used to release structural polysaccharides (hemicelluloses) from plant tissues. Chromatography (Sephadex G-25) of the ethanol-water extract from wood and the alkaline extract from leaves demonstrated that Tc in these extracts was not principally TcO-4 but was complexed with molecules greater than 1000 amu. Incubations of leaf and wood homogenates with protease approximately doubled the amount of Tc released from contaminated tissues. Ultrafiltration of protease-solubilized Tc from leaves and wood showed that 40% and 93%, respectively, of the Tc was less than 10,000 amu. TLC of the less than 10,000 amu fraction indicated the presence of TcO-4 in wood but not in leaves. In the leaf, TcO-4 is converted to less soluble forms apparently associated with structural components of leaf cell walls. This conversion explains why 99Tc is not easily leached by rainfall from tree foliage and why 99Tc appears to accumulate in forest floor leaf litter layers at the Oak Ridge study site.

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Section: Chemical Fractionation Of Tc In Leaves Wood and Littermentioning

confidence: 76%

Technetium-99 Cycling in Maple Trees

Garten¹,

Lomax²

1989

Health Physics

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“…Sel. Technol., Vol. vegetation (19)(20)(21). Last, field concentrations of technetium in soil (<10~3 Mg/g) are far below typical concentrations used in potted-plant studies and are also substantially less than concentrations capable of inducing toxicity in plants.…”

Section: Resultsmentioning

confidence: 98%

Environmental behavior of technetium in soil and vegetation. Implications for radiological assessments

Hoffman¹,

Garten²,

Lucas³

et al. 1982

Environ. Sci. Technol.

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“…Les résultats acquis jusqu'à présent [3,8,9,13] montrent qu'en solution aqueuse, de même qu'en sol bien aéré et en l'absence d'agents réducteurs puis sants, cet élément prédomine sous une forme anionique oxydée [TcO4-: ion pertechnétate] très soluble, très mobile et hautement bioassimilable [21].…”

Section: Introductionunclassified

Etude de l’absorption du technétium 99 par le riz irrigué (Oryza sativa L.)

et al. 1983

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L'absorption du technétium, radionucléide artificiel essentiellement issu du cycle du combustible nucléaire, a été étudiée chez le riz (Oryza sativa L.) en aquiculture et en sol irrigué par une solution contaminée. Les cinétiques d'absorption en flux continu pour différentes concentra tions en 99TC (0,017 à 17 *Ci. I-1) révèlent l'existence de deux phases : la première à dominance passive (diffusion dans les espaces libres) et la seconde, linéaire, résultant de la pénétration du technétium dans les cellules et de ses conséquences. L'évolution de la désorption met en évidence la présence de deux compar timents dont le premier correspondrait aux "espaces libres apparents" tandis que le second, comptant plus des 95 % de l'activité de la plante, représenterait la fraction absorbée. La demi-vie biologique dans ce second compartiment est telle (40 à 50 jours) qu'en cas de pollution accidentelle, une décontamination totale des plantes ne peut être attendue. Comme les essais en aquiculture, les essais en sol montrent l'apparition de symptômes de toxicité pour une concentration dans la solution d'irri gation de 17 / µCi.l-1. Les facteurs de transfert calculés sont très élevés, de l'ordre de 1000 pour les parties aériennes végétatives. La répartition du technétium entre les différentes parties de la plante varie selon la concentration en 99TC mais plus de 90 % sont localisés dans les parties aériennes; les caryopses (parties comestibles) n'en renferment que 1 % .

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Leaching of technetium from foliage by simulated rain

Cited by 17 publications

References 6 publications

Technetium-99 Cycling in Maple Trees

Technetium-99 Cycling in Maple Trees

Environmental behavior of technetium in soil and vegetation. Implications for radiological assessments

Etude de l’absorption du technétium 99 par le riz irrigué (Oryza sativa L.)

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