title: Probing the Kinetic Parameters of Plutonium-Naturally Occurring Organic Matter Interactions in Freshwaters Using the Diffusive Gradients in Thin Films Technique.
abstract: The interaction of trace metals with naturally occurring organic matter (NOM) is a key process of the speciation of trace elements in aquatic environments. The rate of dissociation of metal-NOM complexes will impact the amount of free metal available for biouptake. Assessing the bioavailability of plutonium (Pu) helps to predict its toxic effects on aquatic biota. However, the rate of dissociation of Pu-NOM complexes in natural freshwaters is currently unknown. Here, we used the technique of diffusive gradients in thin films (DGT) with several diffusive layer thicknesses to provide new insights into the dissociation kinetics of Pu-NOM complexes. Results show that Pu complexes with NOM (mainly fulvic acid) are somewhat labile (0.2 ≤ ξ ≤ 0.4), with kd = 7.5 × 10(-3) s(-1). DGT measurements of environmental Pu in organic-rich natural water confirm these findings. In addition, we determined the effective diffusion coefficients of Pu(V) in polyacrylamide (PAM) gel in the presence of humic acid using a diffusion cell (D = 1.70 ± 0.25 × 10(-6) cm(2) s(-1)). These results show that Pu(V) is a more mobile species than Pu(IV).
authors.affiliation: Institute of Radiation Physics, Lausanne University Hospital , 1007 Lausanne, Switzerland.
authors.forename: Ruslan
authors.initials: R
authors.lastname: Cusnir
authors.affiliation: Institute of Radiation Physics, Lausanne University Hospital , 1007 Lausanne, Switzerland.
authors.forename: Maud
authors.initials: M
authors.lastname: Jaccard
authors.affiliation: Institute of Radiation Physics, Lausanne University Hospital , 1007 Lausanne, Switzerland.
authors.forename: Claude
authors.initials: C
authors.lastname: Bailat
authors.affiliation: Laboratory of Ion Beam Physics, ETH Zurich , 8093 Zürich, Switzerland.
authors.forename: Marcus
authors.initials: M
authors.lastname: Christl
authors.affiliation: Division of Radiation Protection, Federal Office of Public Health , 3003 Berne, Switzerland.
authors.forename: Philipp
authors.initials: P
authors.lastname: Steinmann
authors.affiliation: Division of Radiation Protection, Federal Office of Public Health , 3003 Berne, Switzerland.
authors.forename: Max
authors.initials: M
authors.lastname: Haldimann
authors.affiliation: Institute of Radiation Physics, Lausanne University Hospital , 1007 Lausanne, Switzerland.
authors.forename: François
authors.initials: F
authors.lastname: Bochud
authors.affiliation: Institute of Radiation Physics, Lausanne University Hospital , 1007 Lausanne, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Froidevaux
mesh_terms: D004058:Diffusion; D005618:Fresh Water; D006812:Humic Substances; D007700:Kinetics; D011005:Plutonium
chemical_list: D006812:Humic Substances; D011005:Plutonium