| 1. |
- Yu, Changxun, et al.
(författare)
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Effect of weathering on abundance and release of potentially toxic elements in soils developed on Lower Cambrian black shales, P. R. China
- 2012
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Ingår i: Environmental Geochemistry and Health. - : Springer. - 0269-4042 .- 1573-2983. ; 34:3, s. 375-390
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the geochemical features of 8 soil profiles developed on metalliferous black shales distributed in the central parts of the South China black shale horizon. The concentrations of 21 trace elements and 8 major elements were determined using ICP-MS and XRF, respectively, and weathering intensity (W) was calculated according to a new technique recently proposed in the literature. The data showed that the black shale soils inherited a heterogeneous geochemical character from their parent materials. A partial least square regression model and EFbedrock (enrichment factor normalized to underlying bedrock) indicated that W was not a major control in the redistribution of trace metals. Barium, Sn, Cu, V, and U tended to be leached in the upper soil horizons and trapped by Al and Fe oxides, whereas Sb, Cd, and Mo with negative EF values across the whole profiles may have been leached out during the first stage of pedogenesis (mainly weathering of black shale). Compared with the Chinese average soils, the soils were strongly enriched in the potentially toxic metals Mo, Cd, Sb, Sn, U, V, Cu, and Ba, among which the 5 first listed were enriched to the highest degrees. Elevated concentrations of these toxic metals can have a long-term negative effect on human health, in particular, the soils in mining areas dominated by strongly acidic conditions. As a whole, the black shale soils have much in common with acid sulfate soils. Therefore, black shale soils together with acid sulfate soils deserve more attention in the context of metal exposure and human health.
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| 2. |
- Liu, Weihua, et al.
(författare)
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An empirical examination of the contents and evolution of the composing factors of logistics enterprise competitiveness: a perspective from China
- 2014
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Ingår i: International Journal of Logistics. - : Taylor & Francis Group. - 1367-5567 .- 1469-848X. ; 17:6, s. 459-484
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Tidskriftsartikel (refereegranskat)abstract
- Managers and researchers are increasingly interested in the factor that logistics enterprise competitiveness(LEC) has significant effects on the development of Chinese logistics enterprises, especially in view of theenterprise life cycle. This paper investigates the contents and evolution of the composing factors of LEC inChina by a survey.With Statistical Product and Service Solutions (SPSS 15.0) software, the factor analysismethod is used to determine the effects of each factor on LEC. Furthermore, the comparative analysismethod is applied to compare the composing factors of LEC in different types of logistics enterprises andat different enterprise life cycle stages. The results show that factors of LEC according to their descendingimportance level are corporate capabilities, corporate resources, and dynamic mechanism. Three kindsof corporate capabilities (financial management capability, logistics risk control capability, and humanresource management capability) and two kinds of corporate resources (corporate human resources andcorporate culture) have the greatest influence on the development of LEC, but in reality have poor practicalperformance, and hence deserve more consideration from the enterprises.
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| 3. |
- Peng, Bo, et al.
(författare)
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Geochemistry of major and trace elements and Pb-Sr isotopes of a weathering profile developed on the Lower Cambrian black shales in central Hunan, China
- 2014
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Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 51, s. 191-203
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a geochemical study on the major and trace elements and Pb-Sr isotopes of a weathering profile developed in the Lower Cambrian black shales in central Hunan (China). Six weathering horizons were identified and sampled vertically throughout the profile. The chemical composition of the profile consists of variable concentrations of the major elements Fe2O3, FeO, MnO, MgO, CaO, Na2O, and P2O5 and of less variable concentrations of SiO2, TiO2, Al2O3, and K2O. The chemical change caused by weathering is estimated by mass-balance calculations, and the results show that the element mobility is characterised by substantial loss of SiO2, FeO, CaO, K2O, Na2O, LOI, Cr, V, Ba, Cs, Rb, Sr, U, and Th, and moderate loss of Al2O3, MgO, Fe2O3, Ni, Cu, Pb, Tl, Sn, Sc, Ge and REE (Y). The high field strength elements TiO2, Sn, Sc, U, Ga, Ge, Zr, Hf, Nb, and Ta were immobile during weathering. The chemical changes and the Pb-Sr isotopic data suggest that four types of chemical reactions occurred: the oxidation of sulphide minerals (e.g., pyrite) and organic carbon (OS), the dissolution of less resistant clinochlore-Ia, calcite, and P-bearing minerals (DL), the dissolution of detrital albite and microcline (DA), and the transformation of clay (TC) minerals (e.g., muscovite and illite-smectite). These chemical reactions then led to two stages of geochemical processes, an early stage of chemical differentiation and a later stage of chemical homogenisation. The chemical differentiation dominated by the OS, DL, and DA reactions, led to the leaching of mobile elements (e.g., MgO, Na2O, K2O, P2O5, Sr, and REE) and the redistribution of some less mobile elements (e.g., SiO2 and Al2O3). In contrast, the chemical homogenisation, which was caused by TC reactions, led to the leaching of both mobile and less mobile elements from the system and ultimately transformed the weathered black shales into soil. Soils derived from black shales in South China might result from the above two geochemical processes. (C) 2014 Elsevier Ltd. All rights reserved.
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| 4. |
- Tang, Liqiu, et al.
(författare)
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A Stacking Faults-Containing Silicogermanate with 24-Ring Channels and Unbranched Zweier Silica Double Chains
- 2012
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 12:7, s. 3714-3719
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Tidskriftsartikel (refereegranskat)abstract
- A novel open-framework silicogermanate SU-JU-14 (Stockholm University-Jilin University-Number 14), vertical bar NH3CH2CH2NH3 vertical bar(3)[Ge6.40Si0.60O15(OH)](2)[Ge0.73Si3.27O8], was synthesized by using ethylenediamine as the structure-directing agent under solvothermal conditions. Single-crystal structure analysis reveals that the crystal structure of SU-JU-14 consists of extended 24-ring channels built from [(Ge,Si)(7)O12O6/2(OH)](3-) [(Ge,Si)(7)] clusters and unbranched zweier silica double chains [Ge0.73Si3.27O4O8/2]. Charge neutrality is achieved by diprotonated ethylenediamine guest molecules. The structure consists of stacking faults of layered arrays in two different configurations along the a-axis. SU-JU-14 was characterized by X-ray diffraction, X-ray energy dispersive spectroscopy, scanning electron microscopy, nuclear magnetic resonance, inductively coupled plasma, and thermogravimetric analyses. Crystallographic data: monoclinic, space group C2/c, and unit cell parameters: a = 35.625 (7) angstrom, b = 28.580 (6) angstrom, c = 10.403 (2) angstrom, and beta = 98.30 (3)degrees.
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| 5. |
- Xu, Jingzhe, et al.
(författare)
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Geochemistry of soils derived from black shales in the Ganziping mine area, western Hunan, China
- 2013
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Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 70:1, s. 175-190
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Tidskriftsartikel (refereegranskat)abstract
- The geochemistry of major and trace elements (including heavy metals and rare earth elements) of the fresh and weathered black shales, and the soils derived from black shales in the Ganziping mine area in western Hunan province (China) were studied using the following techniques: X-ray fluorescence (XRF), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray diffraction (XRD). The results show that the black-shale soils are significantly enriched with Al2O3 and Fe2O3, and depleted of mobile elements CaO, Na2O and K2O. The soils are also highly enriched with heavy metals U, V, Ni, Ba, Cu, Zn and Pb, that may cause potential heavy-metal contamination of the soils. Composition of the soils is homogeneous compared to the weathered black shales, for which the concentrations of major elements except CaO and Na2O, and trace elements except heavy metals (U, V, Ni, Ba, Cu, Zn and Pb) as well as the mobile Sr, show lower variations than in the weathered black shales. Ratios of Zr/Hf, Ta/Nb, Y/Ho, Nd/Sm, and Ti/(Ti + Zr), of the soils are also less variable, with values constantly similar to that of the fresh and weathered black shales correspondingly. Thus, components of the soils are believed to be contributed from the parent black shales through weathering and pedogenesis. It is concluded that the soils were formed by at least two stages of geochemical processes: the early stage of chemical differentiation and the later stage of chemical homogenization. The chemical differentiation that was taken during black-shale weathering might have caused the depletion of CaO and Na2O, and the enrichment of Al2O3 and Fe2O3; while the chemical homogenization that was taken during pedogenesis led to the depletion of SiO2 and K2O, and to the further enrichment of Al2O3 and Fe2O3. The heavy-metal enrichment (contamination) of the soils was then genetically related to the enrichment of Al2O3 and Fe2O3 in the soils.
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