Analyzing of uranium species by fluorescence spectroscopy: A contribution for handling ecological problems caused by uranium mining activities in former Eastern Germany


Analyzing of uranium species by fluorescence spectroscopy: A contribution for handling ecological problems caused by uranium mining activities in former Eastern Germany

Baumann, N.; Arnold, T.

As a consequence of extensive and reckless uranium mining in Eastern Germany by the Soviet mining company WISMUT between 1945 and 1990, numerous mining residues exist including important ecological problems in Saxony and Thuringia today. A main topic is washing out mobile uranium species from the rock piles and for-mer mines by surface water. It is necessary to control the pathway, the species, and the amount of migrating ura-nium compounds, and to investigate the interactions between solid mineral phases and mobile uranium species such as sorption, precipitation and forming secondary uranium minerals.
One tool for analyzing tiny amounts of U(VI) species (but also in a minor way U(IV) and U(V) species) is time-resolved laser-induced fluorescence spectroscopy (TRLFS). This method is well established in the Institute of Radiochemistry (IRC) from the Forschungszentrum Dresden-Rossendorf (FZD), especially in case of problems connected with uranium. TRLFS delivers a fluorescence signal with characteristic features in dependence of concentration and speciation of the fluorescent species in the sample. These features are the positions of the peak maxima, and, secondary, characteristic lifetimes of the signals. This technique is applicable in case of U(VI) spe-cies in water solutions, but also in case of thin U(VI) mineral coatings on solid phases.
In that lecture results of investigations of adsorbed uranium species onto mineral surfaces like from gibbsite and from muscovite are presented. Spectroscopic characterisation of several secondary uranium minerals (e.g. bolt-woodite and compreignacite) by determination of the positions of the peak maxima and the lifetimes from the TRLFS signals are presented. The spectroscopic signatures of these uranium (VI) minerals are useful for identi-fying U(VI) mineral species as colloids, as thin coatings on rocks, as minor components in soils, or as alteration products of nuclear waste. Additionally the interaction between an aqueous solution and metallic uranium was investigated by TRLFS: The identification of an ultra-thin secondary mineral film on a disk of metallic depleted uranium (DU) originated from a British tank shell, which was in contact with a phosphate containing solution, will be showed. This example demonstrates the high sensitivity of TRLFS regarding solid U(VI) phases.

Keywords: Uranium mining; U(VI); TRLFS

  • Lecture (others)
    Seminar, 03.11.2008, Bangkok, Thailand

Permalink: https://www.hzdr.de/publications/Publ-11797
Publ.-Id: 11797