Institute of Radiation Physics, Lausanne University Hospital , 1007 Lausanne, Switzerland.
Laboratory of Ion Beam Physics, ETH Zurich , 8093 Zürich, Switzerland.
Environ Sci Technol. 2016 May 17;50(10):5103-10. doi: 10.1021/acs.est.5b05435. Epub 2016 Apr 26.
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).
痕量金属与天然存在的有机物（NOM）的相互作用是水生环境中微量元素形态的关键过程。金属-NOM 配合物的解离速率将影响可用于生物吸收的游离金属量。评估钚（Pu）的生物可利用性有助于预测其对水生生物群的毒性影响。然而，目前尚不清楚天然淡水中 Pu-NOM 配合物的解离速率。在这里，我们使用扩散梯度薄膜（DGT）技术和几种扩散层厚度来提供对 Pu-NOM 配合物解离动力学的新见解。结果表明，与 NOM（主要是富里酸）结合的 Pu 配合物具有一定的不稳定性（0.2 ≤ ξ ≤ 0.4），kd = 7.5 × 10(-3) s(-1)。对富含有机物的天然水中环境 Pu 的 DGT 测量证实了这些发现。此外，我们使用扩散池在腐殖酸存在下确定了 Pu(V)在聚丙烯酰胺（PAM）凝胶中的有效扩散系数（D = 1.70 ± 0.25 × 10(-6) cm(2) s(-1)）。这些结果表明，Pu(V)比 Pu(IV)更具迁移性。
