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[en] In principle, authigenic gypsum and anhydrite are excellent candidates for dating by the uranium-series decay scheme yet have been neglected because of cumbersome dissolution requirements. We present a simplified and manageable procedure for sample dissolution of sulfate minerals using cation-exchange resin. Calcium sulfate is shown to dissolve readily in the presence of cation-exchange resin in the hydrogen from by exchange of Ca2+ for H+. Urandium and thorium isotopes associated with the mineral are released from the solid and fixed on the resin during dissolution. The isotopes are then readily eluted for isolation and analysis by standard alpha spectroscopy techniques. (orig.)
[en] Field experiments on sulphur fertilization in cotton cultivar CIM-I09 were carried out at Central Cotton Research Institute Multan, Pakistan, in silty loam soils. The treatments consisted of four sulphur doses (0, 7, 14, 28 kg ha-l) and two sulphur sources (gypsum and ammonium sulphate). Sulphur fertilization showed significant increase in seed cotton yield, boll number and boll weight. The addition of 7 kg S ha-1 seemed sufficient to overcome deficiency in silty loam soils for optimum cotton production. There were no differences in seed cotton yield due to sulphur sources. The petiole sulphate-sulphur concentration increased with increasing doses of sulphur fertilizer. The concentration of SO/sub 4/-S > 2000 ppm seemed sufficient for normal cotton growth and optimum seed cotton yield. (author)
[en] In spite of the fact that gypsum is one of the most environmentally friendly binders, utilization of gypsum products is relatively narrow. The main problem of gypsum materials is their low resistance to the wet environment and radical decrease of mechanical properties with increasing moisture. The solution of the problem could be in use of composed gypsum-based binders, usually ternary, comprising gypsum, pozzolan and alkali activator of pozzolan reaction. These materials have a better moisture resistance and often also better mechanical properties. Paper provides literature survey of the possible compositions, properties and ways of utilization of the composed gypsum-based binders with latent hydraulic and pozzolan materials together with some results of present research performed by authors. (paper)
[en] The Martian landscape is currently dominated by eolian processes, and eolian dunes are a direct geomorphic expression of the dynamic interaction between the atmosphere and the lithosphere of planets. The timing, frequency, and spatial extent of dune mobility directly reflects changing climatic conditions, therefore, sedimentary depositional ages are important for understanding the paleoclimatic and geomorphologic history of features and processes present on the surface of the Earth or Mars. Optical dating is an established terrestrial dosimetric dating technique that is being developed for this task on Mars. Gypsum and anhydrite are two of the most stable and abundant sulfate species found on the Earth, and they have been discovered in Martian sediments along with various magnesium sulfates and jarosite. In this study, the optical dating properties of various Ca-, Mg-, and Fe-bearing sulfates were documented to help evaluate the influence they may have on in-situ optical dating in eolian environments on Mars. Single-aliquot regenerative-dose (SAR) experimental procedures have been adapted to characterize the radiation dose response and signal stability of the Martian sulfate analogs. Jarosite was dosimetrically inert in our experiments. The radiation dose response of the Ca- and Mg-sulfates was monotonically increasing in all cases with characteristic doses ranging from ∼100 to ∼1000 Gy. Short-term signal fading also varied considerably in the Ca- and Mg-sulfates ranging from ∼0% to ∼40% per decade for these materials. These results suggest that the OSL properties of Ca- and Mg-sulfates will need to be considered when developing protocols for in-situ optical dating on Mars, but more enticingly, our results foreshadow the potential for gypsum to be developed as a geochronometer for Mars or the Earth. - Highlights: → The radiation dose response and OSL signal stability of Ca- and Mg-sulfates was highly variable. → OSL properties of Ca- and Mg-sulfates will need to be considered when developing protocols for in-situ optical dating on Mars. → The results foreshadow the potential for gypsum to be developed as a geochronometer for Mars or the Earth.
[en] The classification and discrimination of minerals are important in geological research. The distribution of rocks and minerals may be inferred based on their identification, which is helpful for the investigation of some geological and environmental evolution problems, either on the earth or on other planets. LIBS and Raman spectra techniques have shown great advantages in simultaneous multi-component, in-situ, and non-destructive detection and they play an important role in rock composition analysis. In this presentation, six kinds of minerals (Gypsum, Spodumene, Barite, Haematite, Moonstone, and Labradorite) were detected by first using LIBS and Raman systems, and then several other methods (PCA, PLS-DA, ANN, and SVM) were used to evaluate the LIBS, Raman, and the fused LIBS/Raman data, respectively. The results indicate the superiority of the fused LIBS/Raman data in mineral classification, which stems from their complementary analysis abilities when studying element composition and structural features. (paper)
[en] The international Phosphogypsum Working Group (PGWG) has its origins in joint meetings of the Stack Free project and the IAEA (2006). These led to formal joint meetings of the IAEA and FIPR (2006, 2007) and to a number of collaborative activities. Out of these activities came two IAEA sponsored meetings on PG, in 2008 and 2009. Another is planned for 2010. The PGWG has adopted the following vision and mission statements. 1. Vision. PG is a resource not a waste. 2. Mission. Find the point of equilibrium between PG production and consumption based on safe, sustainable use. (author)
[en] In this paper, properties of composite materials containing ternary binders are determined. Except gypsum, ternary binders containing also pozzolans and alkaline component, which serve as an activator of pozzolanic reaction. The main aim of this research was to investigate changes in physical and chemical properties and pore structural characteristics due to additions of ternary binders. Experimental results showed that changes in the properties of the composite depend not only on the amount of the addition, but also on the kind of pozzolan. (paper)
[en] The sulfur species existing in different size aerosol particles were determined based on the 'white line' energy shift and the features of post edge structure of sulfur K-edge XANES (X-ray Absorption Near Edge Structure). The results indicated that sulfates were dominant sulfur species in aerosol particles. However, small amount of reductive sulfur species were also found in the ultrafine aerosol particles(<0.1 μm). Sulfates in aerosols mostly exhibited as (NH4)2SO4 and gypsum. Most (NH4)2SO4 distributed in aerosol particles finer than 0.952 μm, while gypsum was the dominant sulfate in coarse aerosols. (authors)
[en] At present, building is considered one of the most polluting activities , however, the sector is becoming aware and taking responsibility for the impact it generates throughout the life cycle of buildings . In the development of the idea of sustainability in the construction, it has been investigated in studies related to the improvement of the conditions of comfort and improvement of the quality of life of the people. In this sense, there are many studies found that intend to incorporate sepiolite for its properties in various materials for the absorption of formaldehydes . Therefore and in view of the results obtained by other authors, the design of a prefabricated panel for indoor false ceiling is proposed. The base material of this panel will be a plaster with sepiolite load in its composition to get it to help improve the indoor air quality of the homes in which it is installed. To achieve the objective, an experimental plan has been developed, divided into three phases: In the first phase, gypsum and plaster were used, following the technical prescriptions of Norma UNE-EN-13279: Yesos de construcción y conglomerantes a base de yeso para la construcción . Said norm, specifies the requirements that this type of material must comply with in terms of hardness, bending and compression, which are the parameters taken into account for this study...