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51.
《Chemie der Erde / Geochemistry》2016,76(3):363-381
The laterite profiles investigated in the present study developed after the emplacement of a slab of oceanic crust and upper mantle sequence (the Semail ophiolite) onto the East Arabian margin during the late Cretaceous. The laterites formed as a result of prolonged weathering of the ophiolite assemblage under tropical to subtropical conditions.Nine laterite profiles have been examined for their Ni potential along a NW-SE segment of the Oman Mountains. The preserved laterite profile shows variations in thickness, mineralogy, and chemical composition. The profiles show a vertical succession from bedrock protolith through saprolite, oxide laterite, to clay laterite. The laterite profiles are unconformably capped either by clastics rocks of the Late Cretaceous Qahlah Formation or by Palaeogene carbonates of the Jafnayn or Abat Formations.The protolith corresponds either to a fine-grained, blackish to greenish serpentinized peridotite or to a coarse-grained dark green altered layered gabbro.The bulk geochemistry of the studied profiles indicates a typical low Ni-laterite pattern in which magnesium (Mg) and silica (Si) become depleted towards the top of the profile, whereas iron (Fe) and aluminum (Al) increase. A significant enrichment in Ni and Co occurred as a result of the laterization process. Ni concentrations average 0.63% (Ibra), 0.72% (East Ibra), 0.67% (Al-Russayl), and 0.33% (Tiwi). Other elements such as Cr, V, Pb, TiO2, Zr, Ba, and Zn were also remobilized across the profiles during the laterization processes. 相似文献
52.
The purpose of the present study was to elucidate in vitro effects of Hg2+, Zn2+, Ni2+ and Cd2+ on cytochrome P4501A1 (CYP1A1) dependent EROD activities in leaping mullet liver microsomes. Fish captured from the most polluted part of Izmir Bay, had highly elevated EROD activities, and induced CYP1A1 protein levels as determined by Western blotting. Although all of the metal ions caused inhibition of the initial velocity of the reaction, Hg2+ and Cd2+ exhibited much higher inhibitory effect at lower concentrations and they were evidently more potent inhibitors than others. The inhibitor concentration giving 50% inhibition (IC50 values) of Zn2+, Ni2+, Cd2+ and Hg2+ of initial EROD activity were 107, 16, 1.3 and 0.15 micromolar, respectively. Glutathione (GSH) at 0.5 mM final concentration, completely reversed Ni2+ and Cd2+ inhibition of EROD activity indicating the protective action of GSH. 相似文献
53.
Megat Ahmad Kamal Megat Hanafiah Haslizaidi Zakaria Wan Saime Wan Ngah 《洁净——土壤、空气、水》2010,38(3):248-256
The adsorption of Ni(II) from aqueous solutions using base treated cogon grass or Imperata cylindrica (NHIC) was performed under batch and column modes. Batch experiments were conducted to determine the factors affecting adsorption such as pH, adsorbent dosage, initial nickel concentration, contact time and temperature. The fixed‐bed column experiment was performed to determine the practical applicability of NHIC and to obtain the breakthrough curve. Adsorption was fast as equilibrium was achieved within 60 min, and was best described by the pseudo second order model. According to the Langmuir model, a maximum adsorption capacity of 6.96 mg/g was observed at pH 5 and at a temperature of 313 K. Thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 were calculated, and indicated that adsorption was a spontaneous and endothermic process. The mechanistic pathway of Ni(II) uptake was examined by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy. The Thomas and Yoon‐Nelson models were used to analyze the fixed‐bed column data. 相似文献
54.
55.
氮、磷对两种微藻吸附与吸收镍的影响 总被引：4，自引：0，他引：4
采用放射性同位素示踪的方法,研究了大量营养盐氮和磷添加对两种微藻:东海原甲藻(Prorocentrum donghaienseLu)和中肋骨条藻(Skeletonema costatum)吸附和吸收重金属镍的影响。结果表明,在短时间(2h)的培养实验中,大量营养盐的添加影响了藻类对重金属的吸附和吸收速率,但氮、磷浓度的增加对藻类吸附和吸收镍的影响有所差异:硝酸盐浓度的添加促进了藻类对镍的吸附和吸收,磷浓度的添加促进了两种藻类对镍的吸附,但对藻类吸收镍的影响不大。在未添加营养盐的条件下,东海原甲藻对镍的吸附量要高于硝酸盐添加组但吸收量则较低,而中肋骨条藻的吸附量和吸收量均较硝酸盐添加组低。当尿素为氮源时,尿素促进了藻类对镍的吸收,其吸收量为同一浓度硝酸盐的1·2倍。本研究结果证明,近海富营养化特别是氮浓度的增加会影响浮游植物对微量金属的吸收,进而可能会影响到金属在整个海洋食物链中的传递。 相似文献
56.
石油中的Ni元素在成因上与原始的生油有机质有关,它是石油生成和运移比较可靠的地球化学指示剂。笔者探讨了油气田上方地表土壤中Ni异常的形成机理,提出了Ni异常的形成至少包括两种地球化学作用,一种是直接渗泄作用,在地表形成正异常;另一种是离子活化转移作用,在油气田上方土壤中形成负异常。文中依据土壤Ni与烃类异常的关系,将Ni异常划分为四种类型,以说明Ni元素与油气的关系,笔者还选用了几个典型实例,展示了土壤Ni在评价构造含油气性中的作用。理论和实践证明,土壤Ni是油气化探中比较有效的辅助指标,应当给予重视。 相似文献
57.
文章为了解决淡水资源短缺这一严峻的问题,考虑将能耗小、无化学再生等优点的膜电容去离子技术作为基础,对其进行改进与优化,即将低电阻、高比表面积和高孔隙率的泡沫镍替代传统集流体。并利用改进后的装置进行实验,分别探讨电极材料、电压和盐水流速等因素对脱盐效率的影响。将未加电极材料和加3种不同的活性炭作为电极材料的装置进行脱盐实验,根据结果得出,在脱盐过程中起主要作用的仍然是电吸附过程,通过进一步对电极材料进行表征,讨论得出脱盐效率与比表面积和孔径分布均有关系。随后在最优电极材料的条件下,讨论得出最优的操作条件,即在施加电压为1.6 V、盐水流速为10 mL/min下可以达到最佳的脱盐效率,吸附量为8.9 mg/g。且通过长时间的吸脱附实验得出电极材料AC1具有良好的再生能力。 相似文献
58.
Controls on variations of platinum-group element concentrations in the sulfide ores of the Jinchuan Ni-Cu deposit, western China 总被引：3，自引：0，他引：3
Ongoing underground exploration in the giant Jinchuan Ni-Cu sulfide deposit in western China is beginning to emphasize the
potential for Cu-, Pt-, and Pd-rich sulfide ores that may have formed by sulfide liquid fractionation. The success of such
an effort relies on whether or not fractional crystallization of sulfide occurred in the Jinchuan system. In this paper, we
used available PGE data to evaluate such a process. We found that about two thirds of the 126 samples analyzed to date exhibit
significant decoupling not only between Pt and Pd but also between Ru, Rh, and Ir. The best explanation for the decoupling
is postmagmatic hydrothermal alteration, which affected not only silicates but also sulfides. The effects of postmagmatic
alteration must be considered when using metal and isotopic ratios to evaluate primary mineralization. PGE variations in the
remaining one third of the samples with Ir/(Ir + Ru) = 0.3–0.7, Ir/(Ir + Rh) = 0.4–0.8, and Pt/(Pt + Pd) = 0.3–0.7 indicate
variable R-factors within individual ore bodies as well as the entire deposit, consistent with the interpretation that multiple
sulfide-bearing magmas from depth were involved in the formation of the Jinchuan deposit. The mantle-normalized PGE patterns
of the least-altered samples from the Jinchuan deposit are similar to the picrite-related Pechenga Ni-Cu sulfide deposit in
Russia. PGE variations that can be related to sulfide liquid fractionation are observed in orebody-1 and orebody-24 but not
in orebody-2 at Jinchuan. Exploration for Cu-, Pt-, and Pd-rich sulfide ores that may have been expelled into fractures in
the footwalls of orebody-1 and orebody-24 appears to be justified. 相似文献
59.
Skadar Lake,the largest lake on the Balkan Peninsula,is famous for a wide range of endemic and rare,or even endangered plant and animal species.Different anthropogenic pressures have,however,influenced the fragile equilibria of the lake ecosystem,with metal pollution as one of the primary concerns.Therefore,this study investigated spatial distribution of metal pollutants in the water and sediment phase of Skadar Lake,and anthropogenic and environmental factors affecting this distribution.A sieving analysis showed that sediment in Skadar Lake is mainly distributed in the three smallest fractions（colloid,clay and silt）.Eleven metals were analyzed in the lake surface and bottom water,and only six of them were detected：potassium,magnesium,calcium,nickel,aluminum and manganese.They were all present at low concentrations.In contrast,sediments contained elevated levels of some metals with concentrations between 28.1-126.8 mg kg~（-1） for Ni,23.6-79.2 mg kg~（-1） for Cr,9.2-36.9 mg kg~（-1） for Cu,199-878 mg kg~（-1） for Mn and 9.6-23.1 g kg~（-1） for Fe.Nickel exceeded consensus-based guidelines for safety towards freshwater dwelling organisms.The organic matter content of the sediment fluctuated between 4.7 and 21.5%.No correlations were found between metal concentrations,organic matter and sediment particle size fractions,suggesting that the latter are not the main factors controlling metal accumulation in Skadar Lake. 相似文献
60.
A new method has been developed that predicts the natural background concentrations of microelements of interest in sediments using the concentrations of various components present in the sample. This is done by developing multiple linear regressions using a dataset which has been selected, using radiochronological dating and statistical methods, to reflect the concentration distributions of natural levels of a large number of sediment constituents. This method is demonstrated in Venice Lagoon, using data generated in a lagoon-wide sampling effort. A quantitative assessment is carried out of the variability of natural background levels at the lagoon scale for the main inorganic microelements, and distribution maps of the background and anthropogenic concentrations of a selected metal (Ni) in sediments at the lagoon scale are presented. With sufficient data, this method can be applied in other areas, allowing for a site-specific separation of natural background and anthropogenic levels of microconstituents in sediments, providing insights into regional geochemistry and aiding in the risk-based management of coastal sediments. 相似文献