Curium(III) speciation studies with cells of a groundwater strain of Pseudomonas fluorescens

Ubiquitous Pseudomonads have great potential to influence the speciation and mobility of actinides in the environment. This study explores the unknown interaction between curium(III) and cell-suspensions of Pseudomonas fluorescens (CCUG 32456) isolated from the Äspö site, Sweden.
The interaction between curium(III) and P. fluorescens cells was studied at trace curium(III) concentrations (0.3 µM) using time-resolved laser-induced fluorescence spectroscopy. Extraction studies have shown that the biosorption of curium(III) is a reversible process. Two Cm3+-P. fluorescens (CCUG 32456) species could be identified, R-O-PO3H-Cm2+ and R-COO-Cm2+, having emission maxima at 599.6 and 601.9 nm, respectively. The corresponding surface complexation constants were determined to be log β111 = 12.7 ± 0.6 and log β110 = 6.1 ± 0.5, respectively.