[en] Geochemical studies on the alluvial aquifer system near the Nakdong River were carried out for the basic investigation of the estimation of artificial recharge for the river bank filtration. In-situ data do not show any distinct difference between the pumping well and river. Most of waters belong Ca-HCO3 and Ca-SO4 types and show high Mn concentration. In the borehole installed with Multi-packer (MP) system, Na, Ca, Mg, HCO3 contents of the groundwater are increased with depth increasing. Cl and SO4 contents of the groundwater show the lowest values at the bottom level (18m depth) and Mn content is very high at the middle level (13.5m depth) of MP system. There is no distinct difference in the δ18O and D values and tritium content between MP, borehole and surface water samples. The sulfur isotope data indicate that the possible sulfur source is dissolution of sulfate mineral from sedimentary rock. Strontium isotope ratio shows a little differences between the pumping well and observation borehole samples. Nitrogen isotope data indicate that the nitrogen of water samples is originated from fertilizer or organic materials

[en] Foliar application of liquid organic fertilizer, compost water extract, combined with micronutrients solution in sulfate form, EDTA form or humic acid form gave the highly significant values for fenugreek plants height and weight of seeds. Seven treatments such as compost tea, every three forms of micronutrients and three combinations (1:1) of compost tea with each micronutrients form besides untreated control were applied as foliar spray twice to Trigonella plants at 35 days and at 70 days from sowing. The plant height increments were by 48 and 50% for sulfate form with compost tea, by 67 and 69% for humic acid form with compost tea and by 66% for EDTA form with compost tea for the first and second season, respectively. The values of fenugreek weight of seeds for combined compost tea in both seasons were by (63 and 41%) with sulfate mineral solution, by (76 and 50%) with EDTA and by (90 and 65%) with humic acid, respectively. It is obvious from the results that using compost tea in a combination with micronutrients forms can reduce the chemical fertilizer dose by 50% and enhance the fenugreek growth better than the chemical fertilizer does.

[en] The speciation of uranyl in sulfate-bearing solutions at temperatures up to 250 °C has been investigated using in situ UV-Visible spectrophotometry. Formation constants for the reactions UO${}_2^{2+}$ + SO${}_4^{2\text{–<!-- ??? -->}}$$⟺<!--\; ???\; -->$ UO₂SO${}_4^0$ (logβ₁ = 3.38, 4.40, 5.44, 6.33, 7.74) and UO${}_2^{2+}$ + 2SO${}_4^{2\text{–<!-- ??? -->}}$$⟺<!--\; ???\; -->$ UO₂(SO₄)${}_2^{2\text{–<!-- ??? -->}}$ (logβ₂ = 4.10, 5.26, 6.83, 8.00, 9.70) derived at 25, 100, 150, 200 and 250 °C respectively. These formation constants were fitted to the modified Ryzhenko – Bryzgalin (MRB) model to derive pK(298), A(zz/a) and B(zz/a) values for both complexes: 3.262, 2.212, -197.96 (UO₂SO${}_4^0$) and 4.189, 3.21, -473.14 UO₂(SO₄)${}_2^{2\text{–<!-- ??? -->}}$ respectively. Compared with values extrapolated using previously available data for 25, 70 and 75 °C, our new data suggest higher stability of UO₂SO${}_4^0$ at temperatures above 150 ºC and significantly lower stability of UO₂(SO₄)${}_2^{2\text{–<!-- ??? -->}}$ at all temperatures above 25 °C. Molar absorbances of both sulfate species were also derived. At 25 °C we found our molar absorbance for UO₂SO${}_4^0$ agreed well with those reported previously in the literature, however we report lower peak amplitudes for UO₂(SO₄)${}_2^{2\text{–<!-- ??? -->}}$ . We also noted significant temperature-dependent red shifts in the molar absorbance of UO₂SO${}_4^0$. We imply that these shifts could be explained by changes in sulfate bonding behaviour around the uranyl O04 ion - namely shifts in the distribution of complexes with sulfate bound in either a monodentate or bidentate configuration. Simple models calculated with our new data suggest that sulfate complexes may readily predominate over chloride complexes even in solutions containing upwards of 20 wt% chloride and only 100 ppm sulfate. In addition, moderate concentrations of sulfate (~1 wt%) can increase the solubility of uranium by an order of magnitude. Therefore, we imply that sulfate could play a vital role in mobilising uranium in hydrothermal systems, and that the removal of sulfate via precipitation of sulfate minerals may act as a means of depositing uranium under oxidizing conditions. This in turn might explain the associations between sulfate minerals and uranium mineralisation occasionally seen in large uranium ore deposits such as Olympic Dam and MacArthur River.

[en] As jarosite and oxalic acid are ubiquitous in nature, we investigated a remediation technology for uranium-contaminated site by photoinduced reduction coupled with adsorption of jarosite. Jarosite exhibited excellent adsorption properties for uranium, with a highest adsorption capacity 453.98 mg g^-1. With the presence of oxalic acid, U(VI) was removed at a reduction ratio of 30.71% under irradiation. It may be that oxalic acid promoted the reduction of Fe(III) to Fe(II) in jarosite, and then Fe(II) reduced U(VI) to U(IV). The results confirmed the applicability of the remediation by adsorption using jarosite and light-induced reduction. (author)

[en] Short note

[en] The crystal structure of nikischerite, Na Fe²⁺₆ Al₃ (SO₄)₂ (OH)₁₈ (H₂O)₁₂, rhombohedral, a 9.347(1), c 33.000(7) A, V 2497(3) A³, Z = 3, R₃^-, has been refined to an R index of 6.4% using 444 observed reflections measured with MoKα X-radiation. The structure of nikischerite consists of planar [AlFe²⁺(OH)₆] sheets of octahedra that are intercalated with (Na{H₂O}₆) octahedra, (SO₄) tetrahedra and (H₂O) groups, all units being linked by hydrogen bonds. Nikischerite is isostructural with shigaite, Na Mn-6²⁺₆ Al₃ (SO₄)₂ (OH)₁₈ (H₂O)₁₂, and motukoreaite, ideally Na Mg₆ Al₃ (SO₄)₂ (OH)₁₈ (H₂O)₁₂. (author)

[en] In this revision the state of the knowledge is presented with respect to the understanding of the nature of the active places for the strongly acid solid catalysts of the type sulphated metallic oxides. The results presented by means of models are based on the characterization of the properties physicochemical carried out by means of technical as XPS, to GO, NMR etc., and the evaluation of the catalytic activity in different applications

[en] Short communication. 23 refs, 12 figs

[en] The uranyl sulphate mineral zippeite was studied by Raman spectroscopy. The phase purity of the sample was initially checked by X-ray powder diffraction and its chemical composition was defined by electron microprobe (wavelength dispersive spectroscopy, WDS) analysis. The Raman spectroscopy research focused on the low wavenumber and uranyl stretching vibration regions. Vibration bands down to 50 cm^-1 were tentatively assigned. The U-O bond lengths were calculated based on empirical relations. Inferred values are consistent with those obtained from the crystal structure analysis of synthetic zippeite. Number of bands was interpreted on the basis of factor group analysis. (orig.)

No abstract available