title: Solution speciation of plutonium and Americium at an Australian legacy radioactive waste disposal site.
abstract: During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at the Little Forest Burial Ground (LFBG), located near the southern suburbs of Sydney, Australia. Because of periodic saturation and overflowing of the former disposal trenches, Pu and Am have been transferred from the buried wastes into the surrounding surface soils. The presence of readily detected amounts of Pu and Am in the trench waters provides a unique opportunity to study their aqueous speciation under environmentally relevant conditions. This study aims to comprehensively investigate the chemical speciation of Pu and Am in the trench water by combining fluoride coprecipitation, solvent extraction, particle size fractionation, and thermochemical modeling. The predominant oxidation states of dissolved Pu and Am species were found to be Pu(IV) and Am(III), and large proportions of both actinides (Pu, 97.7%; Am, 86.8%) were associated with mobile colloids in the submicron size range. On the basis of this information, possible management options are assessed.
authors.affiliation: School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ikeda-Ohno
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Harrison
authors.forename: Sangeeth
authors.initials: S
authors.lastname: Thiruvoth
authors.forename: Kerry
authors.initials: K
authors.lastname: Wilsher
authors.forename: Henri K Y
authors.initials: HK
authors.lastname: Wong
authors.forename: Mathew P
authors.initials: MP
authors.lastname: Johansen
authors.forename: T David
authors.initials: TD
authors.lastname: Waite
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Payne
mesh_terms: D000576:Americium / Q000737:chemistry* / Q000302:isolation & purification*; D001315:Australia; D011232:Chemical Precipitation; D003102:Colloids / Q000737:chemistry; D064371:Hazardous Waste Sites; D010316:Particle Size; D011005:Plutonium / Q000737:chemistry* / Q000302:isolation & purification*; D011850:Radioactive Waste / Q000032:analysis*; D012987:Soil; D012996:Solutions; D014875:Water Pollutants, Radioactive / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D003102:Colloids; D011850:Radioactive Waste; D012987:Soil; D012996:Solutions; D014875:Water Pollutants, Radioactive; D011005:Plutonium; D000576:Americium