Probing the Kinetic Parameters of Plutonium–Naturally Occurring Organic Matter Interactions in Freshwaters Using the Diffusive Gradients in Thin Films Technique

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• 作者：Ruslan Cusnir ; Maud Jaccard ; Claude Bailat ; Marcus Christl ; Philipp Steinmann ; Max Haldimann ; François Bochud ; Pascal Froidevaux
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：May 17, 2016
• 年：2016
• 卷：50
• 期：10
• 页码：5103-5110
• 全文大小：334K
• 年卷期：0
• ISSN：1520-5851

文摘

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 k_d = 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 cm² s^–1). These results show that Pu(V) is a more mobile species than Pu(IV).