Molecular and microscopical characterization of the algae mat from the „Gessenhalde“ (Ronneburg/Eastern Thuringia) and the proof of the retention of uranium


Molecular and microscopical characterization of the algae mat from the „Gessenhalde“ (Ronneburg/Eastern Thuringia) and the proof of the retention of uranium

Zirnstein, I.; Krawczyk-Bärsch, E.; Arnold, T.; Röske, I.

Next to the test-field site of the former uranium leaching dump “Gessenhalde” (Ronneburg/Eastern Thuringia), which is part of a research program of the Friedrich-Schiller University, biofilms were sampled from a creek and investigated by PCR and cloning, light microscopy, CLSM and TEM/EDX. The molecular and microscopical characterization of the eukaryote diversity showed a wide spectrum of free living eukaryote microorganism, like the filamentary green algae Microspora and Klebsormidium as the dominant eukaryote. Flagellates, ciliates and rotaroria are present as representatives of the protozoa in minor amount. The water of the creek is characterized by a low pH of 3.3 – 3.9 and a uranium concentration, which ranges seasonally between 1x10-6 M/L and 6x10-6 M/L. Following up the question if the algae mat may have immobilized uranium by biosorption or bioaccumulation the filamentary algae were selected and investigated microscopically and spectroscopically by CLSM and TEM/EDX. Since the results did not provide any microscopic and spectroscopic evidence for the presence of uranium immobilization, the filamentary algae were cultured in rain water with a pH adjusted to 6,0. After the addition of uranium as UO2(ClO4)2 in the ecologically relevant concentration of 1x10-5 M/L the algae showed characteristic fluorescence spectra in the wavelength range of 480-560 nm, which is typical for uranium (VI). The results demonstrated that the actual in-situ geochemical conditions of the creek from the "Gessenhalde" inhibit the retention of uranium by the algae mat. The removal of uranium from the aqueous phase requires the cultivation of algae in a neutral media.

Keywords: biofilm; algae; uranium

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    9. Sanierungskolloquium, 04.-05.10.2010, Jena, Deutschland

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Publ.-Id: 14436