Solid partitioning and solid-liquid distribution of 210Po and 210Pb in marine anoxic sediments: roads of Cherbourg at the northwestern France.
A sequential extraction protocol has been used to determine the solid-phase partition of (210)Po and (210)Pb in anoxic marine sediment from the roads of Cherbourg (France) in the central English Channel. Measurements were also obtained in pore waters, in which (210)Po activities range between 1 and 20 mBq L(-1) and (210)Pb activities between 2.4 and 3.8 mBq L(-1), with highest activities in the topmost layer. These activities are higher than in seawater, suggesting that sediment act as a source of both (210)Po and (210)Pb for overlying water. The (210)Po profile in the pore waters is apparently correlated with those obtained for Fe, Mn and SO(4)(2)(-), suggesting an influence of early diagenetic processes on the (210)Po solid-liquid distribution. In the sediment, (210)Po is predominantly bound to organic matter or chromium reducible sulphides, and residuals (clay minerals and refractory oxides). Our results indicate that (210)Po is not significantly bound to AVS, i.e. acid volatile sulphides: bioturbation could play a role by the early redistribution of (210)Po bound to acid volatile sulphides in the sediment. (210)Po, (210)Pb and Pb exhibit differences in terms of distribution, probably due to a different mode of penetration in the sediment. This work provides information on solid and liquid distribution of (210)Po and (210)Pb in marine sediment. These data are very scarce in the literature.
Connan
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Laboratoire de Radioécologie de Cherbourg-Octeville, Institut de Radioprotection et de Sureté nucléaire (IRSN), Service d'Etudes et du Comportement des Radionucléides dans l'Environnement (SECRE), rue Max Pol Fouchet, Cherbourg-Octeville, France. olivier.connan@irsn.fr
Boust
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D
Billon
G
G
Solier
L
L
Rozet
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M
Bouderbala
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S
D005602:France; D019015:Geologic Sediments / Q000737:chemistry*; D007700:Kinetics; D007856:Lead Radioisotopes / Q000032:analysis*; D011059:Polonium / Q000032:analysis*; D011834:Radiation Monitoring; D012623:Seawater / Q000737:chemistry*
D007856:Lead Radioisotopes; D011059:Polonium