Isotopic fractionation of tritium in biological systems.
Isotopic fractionation of tritium is a highly relevant issue in radiation protection and requires certain radioecological considerations. Sound evaluation of this factor is indeed necessary to determine whether environmental compartments are enriched/depleted in tritium or if tritium is, on the contrary, isotopically well-distributed in a given system. The ubiquity of tritium and the standard analytical methods used to assay it may induce biases in both the measurement and the signification that is accorded to the so-called fractionation: based on an exhaustive review of the literature, we show how, sometimes large deviations may appear. It is shown that when comparing the non-exchangeable fraction of organically bound tritium (neOBT) to another fraction of tritium (e.g. tritiated water) the preparation of samples and the measurement of neOBT reported frequently led to underestimation of the ratio of tritium to hydrogen (T/H) in the non-exchangeable compartment by a factor of 5% to 50%. In the present study, corrections are proposed for most of the biological matrices studied so far. Nevertheless, the values of isotopic fractionation reported in the literature remain difficult to compare with each other, especially since the physical quantities and units often vary between authors. Some improvements are proposed to better define what should encompass the concepts of exchangeable and non-exchangeable fractions.
CEA Valduc, 21120 Is-sur-Tille, France; UMR CNRS 6249 Chrono-Environnement, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex, France. Electronic address: pierre.legoff@cea.fr.
Pierre
P
Le Goff
UMR CNRS 6249 Chrono-Environnement, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex, France.
Michel
M
Fromm
CEA Valduc, 21120 Is-sur-Tille, France.
Laurent
L
Vichot
UMR CNRS 6249 Chrono-Environnement, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex, France.
Pierre-Marie
PM
Badot
CEA/HC, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France.
Philippe
P
Guétat
D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D010944:Plants / Q000737:chemistry; D011835:Radiation Protection; D014316:Tritium / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry
D004785:Environmental Pollutants; D014867:Water; D014316:Tritium
Environment; Isotopic fractionation; OBT; Tritium