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2 Publications
Uranium speciation of environmentally related waters
Geipel, G.; Bernhard, G.;
In the environment uranium is one of the ubiquitous elements. One million tons of uranium metal have been produced so far. Between 1945 and 1990 about one quarter of the total world production of uranium have been mined and milled in Eastern Germany. Especially these former intense uranium mining and milling activities have caused contaminations within urban areas.

In the hexavalent oxidation state uranium is soluble in aqueous media. The determination of different species with non-invasive methods can be performed by Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLIFS) under natural conditions. This is due to the different fluorescence emission and fluorescence lifetime of the varying uranium species.
The concentration of uranium ranges from the upper ng/L scale for table waters to the mg/L scale for mining related seepage and surface waters of the tailing ponds. From speciation calculations uranium in the most of these waters should be found as carbonate species. Unfortunately the carbonate species show poor fluorescence properties under ambient temperatures. By cooling of the samples to temperatures below 220 K an increase in the fluorescence intensity and lifetime can be observed. The dynamic quench effect of the carbonate ion decreases with decreasing temperature. Therefore the direct determination of the uranium speciation also in drinking waters can be performed. Examples of uranium carbonate speciation in a wide variety of natural waters will be given.

As an example, the dependence of the uranium speciation on pH of a tailing pond water was detected in detail by TRLIFS measurements. This water contains complexing anions like carbonate, phosphate, arsenate and sulphate. The uranium speciation in this surface water is strongly changed with pH. At pH 5 uranium arsenate species are dominating. The fluorescence emission of this species is in good agreement with data obtained from the uranium mineral troegerite.
Keywords: uranium, speciation, fluorescence, spectroscopy
  • Invited lecture (Conferences)
    Western Pacific Geophysics Meeting, 24.-27.07.2006, Beijing, China
  • Contribution to proceedings
    Western Pacific Geophysics Meeting, 27.07.2006, Beijing, China
    Uranium speciation of environmentally related waters

Publ.-Id: 8339