Curium(III) as intrinsic luminescence probe for direct speciation studies in biogeochemical systems

Knowledge concerning the speciation of actinides is essential to understand their fate and behavior in the environment. Moreover, the speciation of actinides influences their behavior in biological systems (e.g., microbes) in terms of chemical toxicity and radiotoxicity. Since many years we are successfully operating a unique pulsed flash lamp pumped Nd:YAG-­OPO laser system (Powerlite Precision II 9020 laser equipped with a Green PANTHER EX OPO from Continuum, Santa Clara, CA, USA) designed especially to detect the luminescence of trivalent actinides and lanthanides (e.g., Cm, Eu). The luminescence spectra were detected using an optical multi-channel analyzer-system, consisting of an Oriel MS 257 monochromator and spectrograph with a 300 or 1200 line mm-1 grating and an Andor iStar ICCD camera (Lot-Oriel Group, Darmstadt, Germany). The potential of this system for direct speciation studies of Curium(III) in biogeochemical systems will be presented on the basis of selected examples. These examples cover geochemical systems: the aqueous Cm(III) phosphate system [1] and biological systems: (a) Cm(III) speciation studies with cells of a groundwater strain of Pseudomonas fluorescens [2] and (b) Cm(III) complexation with bacterial surface-layer proteins [3].

Acknowledgement: This work was partly funded by BMWi under contract number 02E10618. The authors are indebted to the U.S. Department of Energy, Office of Basic Energy Sciences, for the use of 248Cm via the transplutonium element production facilities at Oak Ridge National Laboratory; 248Cm was made available as part of collaboration between HZDR and the Lawrence Berkeley National Laboratory (LBNL).

[1] Moll, H. et al. (2011) Radiochim. Acta 99, 775-782.
[2] Moll, H. et al. (2012) Geomicrobiol. J., in press.
[3] Moll, H. et al. (2011) Poster at the 13th International Conference on the Chemistry and Migration Behavior of Actinides and Fission Products (MIGRATION 2011), 18.-23.09.2011, Beijing, PR China.