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1.
The Eaton ‘meteorite’ contains roughly 66 per cent Cu, 33 per cent Zn and <0.1 per cent Ni. In contrast, native Cu from other meteorites contains >90 per cent Cu, <5 per cent Zn and in those samples in which it could be measured, 0.4–2.4 per cent Ni. The major phases and inclusions of Eaton closely resemble those in commercial yellow brass. Eaton contains α and β Cu-Zn, small Pb inclusions around the Cu-Zn crystals and larger Ca aluminosilicate inclusions similar to those from sand casting molds. Based on these data Eaton does not appear to be a meteorite.Both meteoritic and terrestrial native copper are striking for their relatively high purity. Meteoritic Cu appears to be distinguishable from terrestrial material by its higher Ni contents.  相似文献   

2.
The ～200-km-long intensely deformed Singhbhum Shear Zone (SSZ) in eastern India hosts India’s largest U and Cu deposits and related Fe mineralization. The SSZ separates an Archaean cratonic nucleus to the south from a Mesoproterozoic fold belt in the North and has a complex geologic history that obscures the origin of the contained iron-oxide-rich mineral deposits. This study investigates aspects of the history of mineralization in the SSZ by utilizing new petrographic and electron microprobe observations of pyrite textures and zoning in the Turamdih U–Cu(–Fe) deposit. Mineralization at Turamdih is hosted in intensively deformed quartz–chlorite schist. Sulfides and oxides include, in inferred order of development: (a) magmatic Fe(–Ti–Cr) oxide and Fe–Cu(–Ni) sulfide minerals inferred to be magmatic (?) in origin; followed by (b) uranium, Fe-oxide, and Fe–Cu(–Co) sulfide minerals that predate most or all ductile deformation, and are inferred to be of hydrothermal origin; and (c) Fe–Cu sulfides that were generated during and postdating ductile deformation. These features are associated with the formation of three compositionally and texturally distinct pyrites. Pyrite (type-A), typically in globular–semiglobular composite inclusions of pyrite plus chalcopyrite in magnetite, is characterized by very high Ni content (up to 30,700 ppm) and low Co to Ni ratios (0.01–0.61). The textural and compositional characteristics of associated chalcopyrite and rare pyrrhotite suggest that this pyrite could be linked to the magmatic event via selective replacement of magmatic pyrrhotite. Alternatively, this pyrite and associated sulfide inclusions might be cogenetic with hydrothermal Fe-oxide. Type-B pyrite that forms elongate grains and irregular relics and cores of pyrite with high Co contents (up to 23,630 ppm) and high Co to Ni ratios (7.2–140.9) are interpreted to be related to hydrothermal mineralization predating ductile deformation. A third generation of pyrite (type C) with low Co, low Ni, and moderate Co to Ni ratios (0.19–13.93) formed during and postdating the ductile deformation stage overgrowing, replacing, and surrounding type-B pyrite. The textural evolution of pyrite parallels the tectonometamorphic evolution of the shear zone demonstrating grain elongation during progressive ductile deformation and prograde metamorphism, annealing at the peak metamorphic condition, porphyroblastic growth at the retrograde path and cataclasis following porphyroblastic growth. Compositional characteristics of hydrothermal pyrite and available geological information suggest that the U–Cu(–Fe) deposit at Turamdih might be a variant of the Fe oxide (–Cu–U–rare earth elements) family of deposits.  相似文献   

3.
The coarse-grained fraction of C2 chondrites is composed mostly of single crystals and aggregates of crystals of Mg-rich olivine and pyroxene. They do not possess compelling textural evidence of being the solidification products of rapidly-quenched molten droplets. Metal inclusions in the silicates contain 3·82–8·88 mole% Ni, 0·16–0·70 per cent Co, 0·17–1·07 per cent Cr and up to 5·70 per cent P. Thermodynamic calculations show that alloys of these compositions may be condensates from the solar nebula. The implication is that the high-temperature fraction of C2 chondrites consists mostly of high-temperature condensates. Chemical data show that the high-temperature fraction has an Fe/Mg atomic ratio of ? 0·31 compared to 1·3 in the matrix, indicating that much of the iron has been lost from the high-temperature fraction and converted to the troilito and oxidized iron of the low-temperature fraction. The presence of low-Ni metal grains in the aggregates and high Ni/Fe and Co/Fe ratios in the matrix of some C2's indicates preferential loss of early NiCo-rich metal from the high-temperature fraction during condensation.  相似文献   

4.
徐文博  张铭杰  包亚文  满毅  李思奥  王鹏 《地质学报》2022,96(12):4257-4274
塔里木克拉通东北缘坡北、磁海等地二叠纪幔源岩浆活动形成了镍钴硫化物矿床和铁钴氧化物矿床，两者赋矿镁铁 超镁铁岩体的年龄相近(290~260 Ma)，主、微量元素和Sr Nd Hf同位素组成相似，分配系数接近的微量元素比值分布于相同趋势线，揭示两者岩浆源区相同，可能为俯冲板片流体交代的亏损地幔或软流圈地幔。两类矿床镁铁 超镁铁质岩中Co与Ni含量正相关，Co主要富集在基性程度高的岩石中；块状硫化物与磁铁矿矿石中Co与Ni相关性差，Co和Ni具有不同的富集机制，Co热液富集作用明显。北山镁铁 超镁铁杂岩体是地幔柱相关软流圈上涌，诱发俯冲板片交代的亏损岩石圈地幔发生部分熔融，形成的高镁母岩浆演化过程中经历壳源混染、硫化物饱和富集镍钴形成铜镍钴硫化物矿床，富铁母岩浆氧逸度高、富水，岩浆分离结晶磁铁矿、叠加热液作用富集钴，形成铁钴氧化物矿床。  相似文献   

5.
A radioisotope energy-dispersive X-ray (EDX) system has been used on board the German research vessel “Valdivia” during an exploration expedition in the northern equatorial Pacific in 1973. The instrumentation used consisted of an X-ray detection system incorporating a 30 mm2 effective-area Si (Li) detector with a measured energy resolution of 195 eV for Mn Kα X-rays, standard nuclear electronics, a 1024-channel analyser and a data read-out unit. The X-ray spectra in the manganese-nodule samples were excited by a 30-mCi 238Pu source.The six elements Mn, Fe, Co, Ni, Cu and Zn were analysed on board. Precision values for the analyses were less than 3% for Mn, Fe, Ni, Cu and Zn and about 5% for Co. A total amount of 350 analyses was carried out during a one-month cruise.Average contents of 190 analysed whole manganese-nodule samples from all the sampling sites of the covered area were 23.3% Mn, 6.7% Fe, 0.23% Co, 1.16% Ni, 0.94% Cu and 0.10% Zn. The average content of the base metals expressed as the sum of the Co, Ni, Cu and Zn contents was 2.48%. A linear relationship between Mn and Ni in all analysed samples, including whole manganese-nodule samples, zones of manganese nodules and manganese crusts, was observed. The Mn/Ni ratio calculated by regression analysis was 23.0. Zonal variations of the chemical contents of the six elements in the manganese nodules were found. A size classification of the manganese nodules has been suggested. Geochemical correlations of Cu and Ni versus Mn/Fe in the investigated samples are given.  相似文献   

6.
本文通过XRF和ICP-MS测试方法对油页岩样品进行测试,根据常量元素和微量元素特征、组分含量及某些元素的比值,探讨了研究区油页岩样品的地球化学特征,进一步阐述了其沉积环境的指示意义.结果表明,P和B元素强烈富集,相当硼及古盐度值都表明属于半咸水沉积环境,B/Ga、Sr/Ba值也说明受到海水影响或间歇性受海水影响,沉积环境以半咸水湖泊为主;Fe2+/Fe3+、V/(V+Ni)、V/Ni、Cu/Zn、Ni/Co和U/Th值及Ni的含量说明沉积环境为咸化的弱还原—还原环境;Mn/Fe和Mn/Ti值也较小,反映近岸的沉积环境;Sr/Cu表明主力油页岩形成时期处于温湿—干热气候.总体上反映出,研究区油页岩的沉积介质环境的显著特征是半咸水状态的弱还原—还原环境.  相似文献   

7.
The largest occurrence of natural metallic iron on Earth is on the island of Disko, Greenland. Metallic iron is found there in a variety of different types, from small metal particles in basalts to large meter-sized blocks. We have studied three different types of metallic iron: small metal spherules (< 300 m) in basaltic magma; larger metal grains (300 m-3 mm), often composed of aggregates of smaller particles, in similar host rocks; and massive iron lumps (up to several tons). Analytical data for 13 siderophile elements in samples from these three types are presented. All metals analysed have a distinctly crustal pattern of siderophile elements. High Co/Ni, Re/Ir or W/Ir ratios clearly demonstrate that a meteoritic origin for the metallic iron must be excluded. Since the Co/Ni and Re/Ir ratios are approximately chondritic in the upper mantle of the Earth, a mantle origin for the Disko metals can also be ruled out. This supports earlier petrological and geological evidence that the metallic iron was formed through reduction of basaltic magma by carbon derived from Tertiary shales and coals. Significant differences in absolute and relative abundances of siderophile elements occur among the three kinds of metals. The strongly siderophile elements (e.g. Ir, Re, Ni) increase in concentration from the small metal spherules through the larger grains to the massive iron lumps. The contents of less strongly siderophile elements (P, W, Ga) decrease in the same sequence. Evidence is presented that the small metal spherules are formed by in situ reduction. Larger iron metal grains and massive iron lumps are composed of small spherules, accumulated by gravitational settling in a magma reservoir. These metal cumulates have extracted highly siderophile elements from a larger volume of basaltic melt.Part of a Ph.D. thesis by W. Klöck  相似文献   

8.
Reported in this paper are structural and compositional data as the basis for the classification of 35 iron meteorites. The Xingjiang iron meteorite, previously labelled IIIAB, is reclassified as IIIE on the basis of its lower Ga/Ni and Ge/Ni ratios, its wider and swollen kamacite bands and the ubiquitous presence of haxonite, (Fe, Ni)23C. IIICD Dongling appears not to be a new meteorite, but to be paired with Nandan. Four Antarctic iron meteorites IAB Allan Hills A77250, A77263, A77289 and A77290 are classified as paired meteorites based on their similarities in structure, and the concentrations of Cr, Co, Ni, Cu, Ga, Ge, As, Sb, W, Re, Ir and Au. It is found that Cu shares certain properties with Ga and Ge, which makes it an excellent taxonomic parameter. BecauseK Cu is near unity, Cu displays a small range of variation within most magmatic groups (less than a factor of 2.2) and, because of its high volatility, large variations can be noticed among groups.  相似文献   

9.
《Applied Geochemistry》1998,13(2):213-233
Porewater concentration profiles were determined for Fe, trace elements (As, Cd, Co, Cu, Mn, Ni, Pb, Zn), sulfide, SO4 and pH in two Canadian Shield lakes (Chevreuil and Clearwater). Profiles of pyrite, sedimentary trace elements associated with pyrite and AVS were also obtained at the same sites. Thermodynamic calculations are used, for the anoxic porewaters where sulfide was measured, to characterize diagenetic processes involving sulfide and trace elements and to illustrate the importance of sulfide, and possibly polysulfides and thiols, in binding trace elements. The ion activity products (IAP) of Fe sulfide agree with the solubility products (Ks) of greigite or mackinawite. For Co, Ni and Zn, IAP values are close to the KS values of their sulfide precipitates; for Cu and Pb, IAP/Ks indicate large oversaturations, which can be explained by the presence of other ligands (not measured) such as polysulfides (Cu) and thiols (Pb). Cobalt, Cu, Ni and Zn porewater profiles generally display a decrease in concentration with increasing ΣH2S, as expected for transition metals, whereas Cd, Pb and Zn show an increase (mobilisation). The results suggest that removal of trace elements from anoxic porewaters occurs by coprecipitation (As and Mn) with FeS(s) and/or adsorption (As and Mn) on FeS(s), and by formation of discrete solid sulfides (Cd, Cu, Ni, Pb, Zn and Co). Reactive Fe is extensively sulfidized (51–65%) in both lakes, mostly as pyrite, but also as AVS. Similarities between As, Co, Cu and Ni to Fe ratios in pyrite and their corresponding mean diffusive flux ratios suggest that pyrite is an important sink at depth for these trace elements. High molar ratios of trace elements to Fe in pyrite from Clearwater Lake correspond chronologically to the onset of smelting activities. AVS can be an important reservoir of reactive As, Cd and Ni and, to a lesser extent, of Co, Cu and Pb. Overall, the trace elements most extensively sulfidized were Ni, Cd and As (maximum of 100%, 81% and 49% of the reactive fraction, respectively), whereas Co, Cu, Mn, Pb and Zn were only moderately sulfidized (11–16%).  相似文献   

10.
San Cristobal is an unusual group IB ataxite with 25 per cent Ni, composed of taenite grains 2–3 cm in diameter and silicate-troilite-graphite nodules concentrated on the grain boundaries. Silicate compositions are typical of group IAB: olivine Fa3.3, orthopyroxene Fs6.9 and feldspar Ab88. Plagioclase shows peristerite unmixing, previously unrecorded in meteorites, and occasional K-rich feldspar grains have an unusual antiperthite exsolution. Brianite Na2CaMg(PO4)2 and haxonite (Fe, Ni)23C6 are common in nodules and matrix, respectively, while cohenite is rare. Part of the matrix contains a pearlitic kamacite precipitate instead of the usual oriented platelets.San Cristobal has extreme concentrations of many elements; e.g. the highest published Ag, Cu, In and Sb contents and the lowest Mo and Pt in irons. These data and the mineralogy show that San Cristobal has many characteristics of both groups IB and IIID, but that it fits group IB trends better. Ratios of refractory element abundances to those in Cl chondrites (both normalized to Ni) decrease through IB from l in IA to 0.03 in San Cristobal, but the other siderophilic elements have a small range of abundance ratios, 0.5–2, throughout IAB. We suggest that IB grains either formed in a part of the solar nebula where refractories had been previously removed, or else failed to equilibrate with a refractory-rich, high-temperature condensate. After condensation of the volatiles, Fe was partially removed, perhaps by oxidation. Group IIICD seems to have experienced similar fractionations. Unlike other iron meteorite groups, neither IAB nor IIICD appears to have been fully molten.  相似文献   

11.
With the aim of better understanding geochemistry of coal, 71 Late Permian whole-seam coal channel samples from western Guizhou Province, Southwest China were studied and 57 elements in them were determined. The contents of Al, Ca, Co, Cr, Cu, Fe, Ga, Hf, K, Li, Mn, Mo, Nb, Ni, Sn, Ta, Ti, Th, U, V, Zr, and REEs in the Late Permian coals from western Guizhou Province are higher than the arithmetic means for the corresponding elements in the US coals, whereas As, Ba, Br, F, Hg, P, Se, and Tl are lower. Compared to common Chinese coals, the contents of Co, Cr, Cu, Ga, Hf, Li, Mn, Mo, Ni, Sc, Sn, Ti, U, V, Zn, and Zr in western Guizhou coals are higher, and As, F, Hg, Rb, Sb, Tl, and W are lower. Five groups of elements may be classified according to their mode of occurrence in coal: The first two, Group A, Tm–Yb–Lu–Y–Er–Ho–Dy–Tb–Ce–La–Nd–Pr–Gd–Sm, and Group B, As–Sr–K–Rb–Ba–F–Ash–Si–Sn–Ga–Hf–Al–Ta–Zr–Be–Th–Na, have high positive correlation coefficients with ash yield and they show mainly inorganic affinity. Some elements from Group B, such as Ba, Be, Ga, Hf, and Th, are also characterized by significant aluminosilicate affinity. In addition, arsenic also exhibits high sulfide affinity (rS–Fe>0.5). The elements, which have negative or lower positive correlation coefficients with ash yield (with exceptions of Bi, Cs, Nb, Mn, Se, and Ti), are grouped in other four associations: Group C, Cr–V–Mo–U–Cd–Tl; Group D, Hg–Li–Sc–Ti–Eu–Nb–Cs–W; Group E, Bi–Sb; and Group F, Co–Ni–Cu–Pb–Zn–Mg–Se–Ca–Mn–S–Fe. The correlation coefficients of some elements, including Co, Cr, Cu, Fe, Hg, Li, Mo, Ni, P, S, Sc, U, V, and Zn, with ash yield are below the statistically significant value. Only Cr and Cu are negatively correlated to ash yield (−0.07 and −0.01, respectively), showing intermediate (organic and inorganic) affinity. Manganese and Fe are characterized by carbonate affinity probably due to high content of epigenetic veined ankerite in some coals. Phosphorus has low correlation coefficients with any other elements and is not included in these six associations. There are five possible genetic types of enrichment of elements in coal from western Guizhou Province: source rock, volcanic ash, low-temperature hydrothermal fluid, groundwater, and magmatic hydrothermal inputs.  相似文献   

12.
Laser ablation–inductively coupled plasma–mass spectrometry(LA–ICP–MS) was used to determine the trace element concentrations of magnetite from the Heifengshan, Shuangfengshan, and Shaquanzi Fe(–Cu) deposits in the Eastern Tianshan Orogenic Belt. The magnetite from these deposits typically contains detectable Mg, Al, Ti, V, Cr, Mn, Co, Ni, Zn and Ga. The trace element contents in magnetite generally vary less than one order of magnitude. The subtle variations of trace element concentrations within a magnetite grain and between the magnetite grains in the same sample probably indicate local inhomogeneity of ore–forming fluids. The variations of Co in magnetite between samples are probably due to the mineral proportion of magnetite and pyrite. Factor analysis has discriminated three types of magnetite: Ni–Mn–V–Ti(Factor 1), Mg–Al–Zn(Factor 2), and Ga– Co(Factor 3) magnetite. Magnetite from the Heifengshan and Shuangfengshan Fe deposits has similar normalized trace element spider patterns and cannot be discriminated according to these factors. However, magnetite from the Shaquanzi Fe–Cu deposit has affinity to Factor 2 with lower Mg and Al but higher Zn concentrations, indicating that the ore–forming fluids responsible for the Fe–Cu deposit are different from those for Fe deposits. Chemical composition of magnetite indicates that magnetite from these Fe(–Cu) deposits was formed by hydrothermal processes rather than magmatic differentiation. The formation of these Fe(–Cu) deposits may be related to felsic magmatism.  相似文献   

13.
Experiments were carried out between September 2009 and August 2010 at Bei-shi and Gao-mei in Taichung, and at Quan-xing, Chang-Hua and He-mei in Changhua. Dry-deposition flux models of metallic elements Mn, Fe, Zn, Cu and Cr bound to air particulates at five characteristic sampling sites were developed. Results concerning metallic elements Mn, Zn, Cr and Cu, revealed that Zhang’s model yielded the best results concerning the dry-deposition flux of particles of size 10 μm at Bei-shi, Chang-Hua, He-mei, Quan-xing and Gao-mei sampling sites. For the metallic element Cr, the model of Noll and Fang exhibited the best dry-deposition flux results for particles of size 10 μm at Bei-shi, He-mei and Gao-mei sampling sites. For metallic element Fe, the model of Noll and Fang yielded the best results for the dry-deposition flux of particles of size 5.6 μm at Bei-shi, Chang-Hua, He-mei and Quan-xing sampling sites. For metallic element Fe, Zhang’s model yielded the best dry-deposition flux results for particles of size 5.6 μm at the Gao-mei sampling site. For ambient air particles, Zhang’s model yielded the best average calculated/modeled ratios for particles of size 3 μm, and the model of Noll and Fang yielded the best average calculated/modeled for particles of size 10 μm. Finally, the models of both Zhang and Noll and Fang yielded more accurate predictions of the dry-deposition of metallic elements in ambient air when the particles were larger than 5.6 μm.  相似文献   

14.
Platinum-group element (PGE) geochemistry combined with elemental geochemistry and magnetite compositions are reported for the Mesoproterozoic Zhuqing Fe–Ti–V oxide ore-bearing mafic intrusions in the western Yangtze Block, SW China. All the Zhuqing gabbros display extremely low concentrations of chalcophile elements and PGEs. The oxide-rich gabbros contain relatively higher contents of Cr, Ni, Ir, Ru, Rh, and lower contents of Pt and Pd than the oxide-poor gabbros. The abundances of whole-rock concentrations of Ni, Ir, Ru, and Rh correlate well with V contents in the Zhuqing gabbros, implying that the distributions of these elements are controlled by magnetite. The fractionation between Ir–Ru–Rh and Pt–Pd in the Zhuqing gabbros is mainly attributed to fractional crystallization of chromite and magnetite, whereas Ru anomalies are mainly due to variable degrees of compatibility of PGE in magnetite. The order of relative incompatibility of PGEs is calculated to be Pd?<?Pt?<?Rh?<?Ir?<?Ru. The very low PGE contents and Cu/Zr ratios and high Cu/Pd ratios suggest initially S-saturated magma parents that were highly depleted in PGE, which mainly formed due to low degrees of partial melting leaving sulfides concentrating PGEs behind in the mantle. Moreover, the low MgO, Ni, Ir and Ru contents and high Cu/Ni and Pd/Ir ratios for the gabbros suggest a highly evolved parental magma. Fe–Ti oxides fractionally crystallized from the highly evolved magma and subsequently settled in the lower sections of the magma chamber, where they concentrated and formed Fe–Ti–V oxide ore layers at the base of the lower and upper cycles. Multiple episodes of magma replenishment in the magma chamber may have been involved in the formation of the Zhuqing intrusions.  相似文献   

15.
Atomic emission spectrographic analysis of the trace inorganic constituents of marine humic substances gave the following range of concentrations: Si, 200 ppm to > 2%; Al, 400 ppm to ~ 1%; Fe, 600–3000 ppm; Ca, 600 ppm to > 2%; Mg, 20–6000 ppm; Na, 600 ppm to > 2%; Ag, < 6–600 ppm; B, < 60–1000 ppm; Cu, 600–4000 ppm; Mn, 8–100 ppm; Mo, <20–3000 ppm; Ni, 100–1000 ppm; Pb, < 40–600 ppm; Sn, 40–600 ppm; Ti, < 20–2500 ppm; V, 20–200 ppm; Zn, 350–4500 ppm; Zr, < 60–500 ppm.Humic substances contain a sizeable portion of the Cu, Mo and Zn found in sediments, but are less important for Ni, Co and Pb, and are insignificant for the Mn, V and Fe content. The metals are mostly introduced into the humates during their diagenetic formation in sediment by dissolution of metals from various mineralogical phases. A precursor of the sedimentary humates, the polymeric organic material dissolved in interstitial water, contains most of the Cu and Zn, about half of the Ni, Fe and Co, and very little of the Mn found in interstitial water. Comparison of the data on humates with that obtained by H2O2 treatment of sediments indicates that Cu, Zn and possibly most of the Mo are associated with organic matter, but that Ni and Co are associated with sulfides.  相似文献   

16.
We have measured diffusion coefficients for P, Cr, Co, Ni, Cu, Ga, Ge, Ru, Pd, Ir, and Au in Fe metal from 1150 to 1400°C and at 1 bar and 10 kbar. Diffusion couples were prepared from high-purity Fe metal and metal from the IIA iron meteorite Coahuila (single crystal kamacite) or the pallasite Springwater (polycrystalline kamacite) and held at run conditions for 3.5 to 123 h. Diffusion profiles were measured using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) or the electron microprobe. Many elements were measured from the same experimental runs so interelemental comparisons are improved over other data sets in which data for different elements come from different experiments. Some literature diffusion coefficients (D) for Ni and Co in taenite can be up to a factor of 3 higher for Ni than Co, yet our results show no difference (e.g., DNi and DCo ∼ 2.2 × 10-15 m2/s at 1150°C). Thus, diffusion of Ni and Co in single crystal taenite will not measurably fractionate the Ni/Co ratio. On the other hand, the large difference in DNi and DIr (DIr is ∼5 times lower) and the similarity of DNi and DRu at all temperatures investigated indicates that Ni/Ir and Ni/Ru ratios in zoned metal grains will be useful discriminators of processes controlled by diffusion vs. volatility. In zoned metal grains in primitive chondrites, deviations of the Ni/Ru and Ni/Ir ratios from a condensation curve are opposite to a diffusion-controlled process, but consistent with a volatility-controlled process. The new multielement diffusion coefficients will also be useful in evaluating a variety of other processes in planetary science.  相似文献   

17.
River water (Water of Luce, Scotland) is used in laboratory experiments designed to investigate physical and chemical properties of Fe. Mn, Cu, Ni, Co, Cd and humic acids in riverine and estuarine systems. Using NaCl, MgCl2 and CaCl2 as coagulating agents, coagulation of dissolved (0.4 μm filtered) Fe, Cu, Ni, Cd and humic acids increases in a similar matter with increasing salt molarily: Ca2+ is the most dominant coagulating agent. Removal by coagulation with Ca2+ at seawater concentrations ranges from large (Fe-80%. HA-60%, Cu-40%) to small (Ni, Cd-15%) to essentially nothing (Cd, Mn-3%). Destabilization of colloids is the indicated mechanism. Solubility-pH measurements show that between a pH of 3 and 9, Fe, Cu, Ni, Mn, Co and Cd are being held in the dissolved phase by naturally occurring organic substances. Between pH of 2.2 and 1.2 a large proportion of dissolved Fe, Cu. Ni and Cd (72, 35,44 and 36% respectively) is precipitated along with the humic acids; in contrast, Mn and Co show little precipitation (3%). Adsorption-pH experiments, using unfiltered river water spiked with Cu, indicate that adsorption of Cu onto suspended particles is inhibited to a large extent by the formation of dissolved Cu-organic complexes.The experimental results demonstrate that solubilities and adsorption properties of certain trace metals in freshwaters can be opposite to those observed with artificial solutions or predicted with chemical models. Interaction with organic substances is a critical factor.  相似文献   

18.
对取自南海西北陆缘海域的大型多金属结核进行了电子探针、X射线粉晶衍射(XRD)、等离子质谱仪(ICP-MS) 和等离子光谱仪(ICP-AES) 等方面的分析.结核核心部位的主要矿物组成为石英、伊利石、钠长石和绿泥石, 壳层的主要矿物为δMnO2等.铁、锰组分呈现Fe含量高、Mn含量低和Mn/Fe低的特征.Si含量高, Cu、Co、Ni含量低; 稀土元素(REE) 含量高, 平均为1472.30×10-6, 轻稀土与重稀土的比值(LREE/HREE) 达19.54, 并且存在较强的Ce正异常.元素含量的变化显示: 从结核内壳层到外壳层, Fe、Mn、Cu、Co等元素含量呈不规律变化, 具有典型的边缘海特征, 该特征反映结核在形成过程中受到边缘海沉积环境波动变化的影响, 陆源物质供应量的增加对Fe、REE、Si等元素的富集起到了促进作用, 而对Mn、Ca等元素的富集则产生明显的稀释作用.多金属结核Mn/Fe比及Mn-Fe- (Cu+Ni) ×10三组分图解显示, 南海北部陆缘多金属结核为水成成因, 该成因与结核所赋存的边缘海环境密切相关, 反映了结核成长发育的过程中, 南海典型的边缘海沉积条件和多变的古海洋环境因素对其产生了重要影响.   相似文献   

19.
Optical emission spectrographic analysis of three pantelleritesfrom Pantelleria and two comendites from Sardinia show highconcentrations of B, Be, Ga, La, Mo, Nb, Sn, Y, Yb, and Zt andlow contents of Ba, Co, Cr, Ni, Sr, and V. Minor-element trendsof these specimens are very similar to those of pantelleritesfrom southern Nevada and New Zealand and other peralkaline silicicrocks from various localities. Fluorine contents of the Pantellerianspecimens range from 0.19 to 0.32 per cent by weight resultingin abnormally high Cl to F ratios. New analyses for MgO, Na2O,and K2O are almost identical with the values obtained by Zies.Revised major-element compositions and calculated glass-phasecompositions for the three Pantellerian specimens are given.  相似文献   

20.
Heavy metal contamination in polished rice grains collected from Hunan Province, Southern China, has been investigated in this study. The concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in rice were determined by microwave-assisted digestion and inductively coupled plasma-mass spectrometry method. In order to evaluate the correlations among heavy metals, statistical analyses including Pearson’s correlation analysis, principal component analysis and hierarchical cluster analysis were performed. Three distinct clusters were classified by the hierarchical cluster analysis approach. In the principal component analysis, three principle components were extracted with the eigenvalue >1.0. The spatial distribution of heavy metals was predicted by the ordinary kriging interpolation. Cu and Ni with similar distribution patterns could be primarily originated from geogenic source. The hot-spot areas in the distribution patterns of Mn, Pb and Zn could be mainly related to mining and smelting activities. Cd and Co might be derived from the combination of natural existence and anthropogenic sources. The chronic non-carcinogenic effect on local rice consumers from exposure to heavy metals was estimated by the target hazard quotient. The average target hazard quotient values of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were 1.754, 0.367, 0.003, 0.544, 0.165, 0.775, 0.228, 0.049 and 0.481, respectively. The target hazard quotient value of Cd exceeded the threshold value suggesting high potential health risk to residents in Hunan Province through rice consumption.  相似文献   

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