Solid partitioning and solid-liquid distribution of 210Po and 210Pb in marine anoxic sediments: roads of Cherbourg at the northwestern France

O. Connan (1) , D. Boust (1) , G. Billon (2) , L. Solier (1) , M. Rozet (1) , S. Bouderbala (1)

1 IRSN/PSE-ENV/SRTE/LRC - Laboratoire de Radioécologie de Cherbourg-Octeville
2 ELICO - Laboratoire de Chimie Analytique et Marine - UPRESA 8013

A sequential extraction protocol has been used to determine the solid-phase partition of 210Po and 210Pb in anoxic marine sediment from the roads of Cherbourg (France) in the central English Channel. Measurements were also obtained in pore waters, in which 210Po activities range between 1 and 20 mBq L-1 and 210Pb 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 210Po and 210Pb for overlying water. The 210Po profile in the pore waters is apparently correlated with those obtained for Fe, Mn and SO42-, suggesting an influence of early diagenetic processes on the 210Po solid-liquid distribution. In the sediment, 210Po is predominantly bound to organic matter or chromium reducible sulphides, and residuals (clay minerals and refractory oxides). Our results indicate that 210Po is not significantly bound to AVS, i.e. acid volatile sulphides: bioturbation could play a role by the early redistribution of 210Po bound to acid volatile sulphides in the sediment. 210Po, 210Pb 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 210Po and 210Pb in marine sediment. These data are very scarce in the litterature. © 2009 Elsevier Ltd. All rights reserved.

Mots clés: Acid volatile sulphide; Anoxic sediments; Bioturbation; Diagenetic process; Different modes; English channel; Liquid distribution; Marine sediments; Organic matter; Overlying water; Pore waters; Refractory oxides; Sequential extraction; Sequential extraction analysis; Solid-liquid; Solid-phase; Chromium; Clay minerals; Lead; Lead alloys; Liquids; Manganese; Manganese compounds; Metal recovery; Organic minerals; Polonium; Positive ions; Roads and streets; Seawater; Sedimentology; Silicate minerals; Submarine geology; Sulfur compounds; Water; Sediments; chromium; lead 210; manganese; mineral; organic matter; oxide; polonium; sea water; sulfate; sulfide; zinc; anoxic sediment; extraction method; lead isotope; marine sediment; partitioning; polonium isotope; porewater; sediment chemistry; article; bioturbation; controlled study; diagenesis; environmental radioactivity; extraction; France; marine environment; radioisotope distribution; sediment; Geologic Sediments; Kinetics; Lead Radioisotopes; Radiation Monitoring; Basse Normandie; Cherbourg; English Channel; Eurasia; Europe; Manche; Western Europe

Domaines: Sciences de l'environnement

O. Connan, D. Boust, G. Billon, L. Solier, M. Rozet, et al.. Solid partitioning and solid-liquid distribution of 210Po and 210Pb in marine anoxic sediments: roads of Cherbourg at the northwestern France. Journal of Environmental Radioactivity, 2009, 100 (10), pp.905-913. ⟨10.1016/j.jenvrad.2009.06.016⟩. ⟨hal-02993484⟩