title: Assessment of surface area normalisation for interpreting distribution coefficients (K(d)) for uranium sorption.
abstract: Adsorption of radionuclides on soils and sediments is commonly quantified by distribution coefficients (K(d) values). This paper examines the relationship between K(d) values for uranium(VI) adsorption and the specific surface area (SSA) of geologic materials. We then investigate the potential applicability of normalising uranium (U) K(d) measurements using the SSA, to produce 'K(a) values' as a generic expression of the affinity of U for the surface. The data for U provide a reasonably coherent set of K(a) values on various solid phases, both with and without ligands. The K(a) representation provides a way of harmonising datasets obtained for materials having different specific surface areas, and accounting for the effects of ligands in different systems. In addition, this representation may assist in developing U sorption models for complex materials. However, a significant limitation of the K(a) concept is that sorption of radionuclides at trace levels can be dominated by interactions with specific surface sites, whose abundances are not reflected by the SSA. Therefore, calculated K(a) values should be interpreted cautiously.
authors.affiliation: Australian Nuclear Science and Technology Organisation, Menai, Australia. tep@ansto.gov.au
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Payne
authors.forename: Vinzenz
authors.initials: V
authors.lastname: Brendler
authors.forename: M Josick
authors.initials: MJ
authors.lastname: Comarmond
authors.forename: Cordula
authors.initials: C
authors.lastname: Nebelung
mesh_terms: D000327:Adsorption; D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry; D008903:Minerals / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D013499:Surface Properties; D014501:Uranium / Q000032:analysis* / Q000737:chemistry; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D008903:Minerals; D012987:Soil; D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive; D014501:Uranium