Uranium in acidic mine drainage from the former Ogoya Mine in Ishikawa Prefecture, Japan, and in neutral surface waters from
its surrounding rivers was investigated from the viewpoint of radioactive disequilibrium in the uranium decay series. Water
samples were periodically collected from the mine pithead and its surrounding rivers and their U isotopes (238U and 234U) were measured together with chemical components. The 238U concentrations in the water samples varied widely from 0.0036 to 0.78 mBq/L with a factor of about 200. High 238U concentrations were observed in the strongly acidic drainage (pH: around 3.5) from the pithead and the 234U/238U activity ratios showed significant values of as high as 10–15. By taking into account of the measurement of Th isotopes,
it appeared that probable processes controlling the high 234U/238U activity ratios in acidic mine drainage were due to that the acidic water flowing from the mine pithead was formed only
in the upper water layer of the pits and 234U was preferentially leached in the deeper underground water under the neutral and reducing conditions.
The aim of this study is to employ a thermogravimetric analyzer coupled to a mass spectrometer to research into the influence
of heating rate and sample mass on the response of the detector. That response is examined by means of a particular efflorescence
taken from an acid mine drainage environment. This mixture of weathered products is mainly composed by secondary sulfate minerals,
which are formed in evaporation conditions, appearing as efflorescence salts. Thermogravimetry coupled to mass spectrometry
has been used to analyze the three main loss steps that happen when this combination of minerals is heated from 30 to 1,100 °C.
This inorganic material is based on a mixture of hexahydrite, zinc sulfate hexahydrate, apjonite, gypsum, plumbojarosite,
calcite, quartz, and magnetite. While heating, three main effluent gases evolved from this efflorescence. At a standard heating
rate of 10 °C/min, loss of water (dehydration) occurred over 30–500 °C in four major steps, loss of carbon dioxide (decarbonisation)
occurred over 200–800 °C in three steps, and loss of sulfur trioxide (desulfation) occurred over 400–1,100 °C in three steps.
According to the results, thermal analysis is an excellent technique for the study of decomposition in these systems.
Ríos C. A., Williams C. D., Roberts C. L. Removal of heavy metals from acidminedrainage (AMD) using coal fly ash, natural clinker and synthetic zeolites, Journal of Hazardous Materials , Vol. 156, No. 1–3, 2008, pp. 23
Macalady L. D., Smith S. K., Ranville F. J. Acidminedrainage; streambed sorption of copper, cadmium and zinc, Colorado Water Resources Research Institute, Completion Report , No. 154, 1990.
Clement R. E., Eiceman G
In situ leaching of uranium ores with sulfuric acid during active uranium mining activity on the Gessenheap has caused longstanding
environmental problems of acid mine drainage and elevated concentrations of uranium. To study there remediation measures the
test site Gessenwiese, a recultivated former uranium mining heap near Ronnenburg/East Thuringia/Germany, was installed as
a part of a research program of the Friedrich-Schiller University Jena to study, among other techniques, the phytoremediation
capacity of native and selected plants towards uranium. In the first step the uranium speciation in surface seepage and soil
pore waters from Gessenwiese, ranging in pH from 3.2 to 4.0, were studied by time-resolved laser-induced fluorescence spectroscopy
(TRLFS). Both types of water samples showed mono-exponential luminescence decay, indicating the presence of only one major
species. The detected emission bands were found at 477.5, 491.8, 513.0, 537.2, 562.3, and 590.7 nm in case of the surface
water samples, and were found at 477.2, 493.2, 513.8, 537.0, 562.4, and 590.0 nm in case of the soil water samples. These
characteristic peak maxima together with the observed mono-exponential decay indicated that the uranium speciation in the
seepage and soil pore waters is dominated by the uranium (VI) sulfate species UO2SO4(aq). Due to the presence of luminescence quenchers in the natural water samples the measured luminescence lifetimes of the UO2SO4(aq) species of 1.0–2.6 μs were reduced in comparison to pure uranium sulfate solutions, which show a luminescence lifetime of
4.7 μs. These results convincingly show that in the pH range of 3.2–4.0 TRLFS is a suitable and very useful technique to study
the uranium speciation in naturally occurring water samples.
Szucs, A., Jordan, G., Qvarfort, U.: 2002. Geochemical modelling of acidminedrainage impact on wetland stream using landscape geochemistry, GIS and statistical methods. In: Fabbri, A.G., Gaal, G., McCammon, R.B.: Deposit and Geoenvironmental Models for