Distribution and concentrations of anthropogenic platinum group elements in the surface environment of Hong Kong

Ecotourism environmental impact assessment is a traveling activity relevant influence prediction and appraisal. And the setting-up of the index system is very important to implement the appraisal of environmental impact of ecological travel. According to the index system, natural ecological environment, humane social environment, the environment of tourist resources and the atmosphere of capacity of tourist environment, four major systems form the first index. Each system formed the second index of several key elements. In addition, it is a key step to appraise the sureness of the factor weight, which influences the rationality of the result directly. Daily method of weighting has the Delphi＇s and the AHP. According to ＂Grade form of characteristic value of Standard of rating for quality of tourist attractions＂ which the National Tourism Administration issues, the paper takes the Jingshan mountains ecological tourist zone as an example and adopts AHP to weight the factors mainly, assisted with the Delphi＇s by the help of computer. The Jingshan ecological tourist zone is good. The result of calculation, comprehensive value of 8.35 after establishment, shows that it doesn＇t change dramatically, attributing to the index of natural ecological environment like atmosphere, quality of surface water, acoustics environment and vegetation coverage. Improvement of traffic states and sanitation caused by the project in the region increases the comprehensive value, while the water and soil loss in partial area caused by construction decrease.     

Content and mode of occurrences of rare earth elements in the Zagrad karstic bauxite deposit (Nikšić area,Montenegro)

Three vertical sections through the Zagrad deposit of Jurassic karst bauxite in central Montenegro have provided knowledge of the vertical distribution of major and some selected trace elements, including rare earth elements (REE). Variations in the mineralogy, particularly those hosting REE, have been studied. This has revealed the presence of authigenic mineral phases such as xenotime, mottramite and monazite (best proved using Raman microprobe analysis) as well as residual phases such as zircon, titanite and monazite. The mobility of the elements during bauxitization processes has been studied to show that the REE minerals ensure progressive concentration of these elements during removal of major elements through weathering. The similarity of normalized REE in the bauxite to the typical Post-Archean Australian Shales (PAAS) and Upper Continental Crust (UCC) profile, and the preserved Eu anomaly, are evidence that the bauxite was not derived from carbonates and represents alteration of shale, marly limestone and volcanogenic or proximal igneous sourced detritus that accumulated in the original karst landform. Mass change during bauxitization, using Ti as “index” element and compared to PAAS composition, revealed almost 100% depletion of Si and weak enrichment in Al. Deeper parts of the deposit with authigenic minerals exhibit very strong enrichment in all REE. The bauxite ores have high ΣREE contents (693.5–6953.4 ppm), especially ΣLREE contents (582.8–4882.9 ppm), while ΣHREE contents (106.6–2070.5 ppm) are much lower.     

The solubility control of rare earth elements in natural terrestrial waters and the significance of PO 4 3− and CO 3 2− in limiting dissolved rare earth concentrations: A review of recent information

Rare earth element (REE) concentrations in alkaline lakes, circumneutral pH groundwaters, and an acidic freshwater lake were determined along with the free carbonate, free phosphate, and free sulfate ion concentrations. These parameters were used to evaluate the saturation state of these waters with respect to REE phosphate and carbonate precipitates. Our activity product estimates indicate that the alkaline lake waters and groundwaters are approximately saturated with respect to the REE phosphate precipitates but are significantly undersaturated with respect to REE carbonate and sulfate precipitates. On the other hand, the acidic lake waters are undersaturated with respect to REE sulfate, carbonate, and phosphate precipitates. Although carbonate complexes tend to dominate the speciation of the REEs in neutral and alkaline waters, our results indicate that REE phosphate precipitates are also important in controlling REE behavior. More specifically, elevated carbonate ion concentrations in neutral to alkaline natural waters tend to enhance dissolved REE concentrations through the formation of stable REE-carbonate complexes whereas phosphate ions tend to lead to the removal of the REEs from solution in these waters by the formation of REE-phosphate salts. Removal of REEs by precipitation as phosphate phases in the acid lake (pH=3.6) is inconsequential, however, due to extremely low [PO ₄ ^3– ] _F concentrations (i.e., 10^–23 mol/kg).     

Trace and rare earth elements in cassiterite — sources of components for the tin deposits of the Mole Granite,Australia

Trace and rare earth elements have been determined for cassiterite from deposits associated with the Mole Granite and hosted by granite, metasediments and metavolcanics. The REE of cassiterite is controlled by the REE of the the ore fluid and the rocks through which this fluid circulated. The REE distribution factor and LREE/HREE value of cassiterite is strongly influenced by the associated mineral assemblage, the fluid chemistry and the crystal chemical characteristics of the host mineral. Cassiterite from deposits hosted by granite have trace and rare earth element characteristics similar to those determined for the Mole Granite. Cassiterite from deposits hosted by metasediments or acid volcanics have most trace and rare earth element characteristics similar to those of the enclosing rocks and some characteristics similar to the Mole Granite. The ore fluid had chemical components derived from the parental granite and components acquired by passage through the metamorphosed aureole.     

Relationship of polycyclic aromatic sulfur compounds and gold enrichment in the Kupferschiefer from Poland and Germany

1INTRODUCTION ORGANICALLY BOUNDSULFURCOMPOUNDSWEREPREVI OUSLYDETECTEDINTHEKUPFERSCHIEFER(P櫣TTMANNAND GO EL,1990;ROSPONDEKETAL.,1994).P櫣TTMANN ANDGO EL(1990)INVESTIGATEDTHEEXTRACTABLEORGANIC MATTERINTHEKUPFERSCHIEFERFROMTHENORTH SUDETIC SYNCLINEANDPROPOS…     

The corrosion of basaltic dykes in evaporites: Ar–Sr–Nd isotope and rare earth elements evidence

The corrosion of basaltic dykes from central Germany which intruded during the Tertiary into rock and potash salts of Upper Permian age (Zechstein) has been studied. The corrosion behavior of these glassy basalts can serve as a natural analogue for the long-term corrosion expected for nuclear waste glasses in a salt repository. Our data demonstrate mobility and fractionation of the rare earth elements (REE) during a postintrusive circulation of salt brines. The processes controlling this behavior of the REE were dissolution and reprecipitation of phosphates. The K–Ar data document the synintrusive assimilation of a salt phase followed by a postintrusive fluid circulation in the peripheral parts. This circulation removed the assimilated salt and imported highly radiogenic salt Ar which was integrated into newly formed sheet silicates. The central part of the dyke was not affected by this circulation and could retain a mantle gas phase. The Sr isotope data document a synintrusive assimilation of salt Sr and a strong exchange with salt fluids during the postintrusive corrosion which was strongest in a zone next to the chilled dyke margins. This locally stronger alteration is probably due to different cooling and shrinking rates of the basalt at the margins and in the core of the dyke which led to the formation of a highly permeable fractured zone.     

The distribution of rare earth elements between monzogranitic melt and the aqueous volatile phase in experimental investigations at 800 °C and 200 MPa

The partitioning of the rare earth elements between a peraluminous monzogranitic melt and a chloride-bearing, sulfur- and carbon dioxide-free, aqueous volatile phase was examined experimentally as a function of chloride and major element concentrations at 800 °C and 200 MPa. The light rare earth elements (e.g. La, Ce) partition into the aqueous volatile phase to a greater extent than the heavy rare earth elements (e.g. Yb, Lu). Distribution of the rare earth elements and the major elements H, Na, K, Ca, and Al between the melt phase (mp) and aqueous volatile phase (aq) is a function of the chlorine concentration in the system, and our data are consistent with the rare earth and major elements occurring as chloride complexes in the aqueous volatile phase. Apparent equilibrium constants for experiments at 800 °C and 200 MPa, K ^′ _REE,Na ^aq/mp , expressed as the ratio of the concentration of a given rare earth element in the aqueous volatile phase to the concentration of the same element in the melt phase, divided by the cubed ratio of sodium in the aqueous volatile phase to the concentration of sodium in the melt phase, decrease systematically with increasing atomic number from K ^′ _La,Na ^aq/mp = 0.41(±0.03) to K ^′ _Lu,Na ^aq/mp =0.11(±0.01), except for Eu. These experimentally derived apparent equilibrium constants for the rare earth elements can be used in a numerical simulation of magmatic volatile exsolution. The simulation gave results consistent with the elemental distribution in the potassic alteration zone of a deep porphyry copper deposit, but higher concentrations of heavy rare earth elements are released into the magmatic aqueous solution than are captured in the secondary mineralization. Received: 1 November 1999 / Accepted: 7 June 2000     

Evolution of silica accumulation in the earth’s history and its relation to biota development

Two branches of silica rockevolution related to oceans and continental blocks have been outlined. The boundaries of changes in types of silica rocks, their formation, and development of the organic world were established: (i) the beginning of the Phanerozoic was related to transformation from microbial to biogenic silica deposition (or to a change in the influence of microbial activity on silica accumulation); (ii) cessation of the formation of cherts enriched in organic matter, which was synchronized with land colonization by organisms in the Devonian, and (iii) an explosive style of global silica accumulation related to the appearance and development of diatoms, which correlates with appearance of angiosperm plants in tropical forests.     

The Role of Organic Matter During Metal Enrichment in Permian Kupferschiefer of the Rudna Mine,Southwest Poland

The bulk composition of organic matter and saturated and aromatic hydrocarbons extracted from 16 samples collected from two Kuperschiefer profiles in the Rudna mine,Southwest Poland has been analyzed to study the role of organic matter during base metal enrichment in the Kupferschiefer shale.The results indicated that the extract yields and saturated hydrocarbon yields decreased with increasing base metal contents.GC and GC/MS analyses indicated that n -alkanes and alkylated aromatic compounds were depleted and may have served as hydrogen donators for thermochemical sulfate reduction.The enrichment of base metal is closely connected with the destruction of hydrocarbons.     

Re–Os age of non-mineralized black shale from the Kupferschiefer, Poland, and implications for metal enrichment

Six samples of non-mineralized black shale from a Kupferschiefer section in the northern part of the Polish Zechstein Basin (Zdrada IG-8 drill hole: 1026.16–1026.90 m) were studied for Re–Os isotopes and selected major and trace elements. These black shales, averaging 5.82 wt.% C_org and 1.69 wt.% S_tot, display very low base metal values (up to 106 ppb Cu, 792 ppb Pb, and 144 ppb Zn) and have abundances of 64–1376 ppb Re and 0.37–1.25 ppb Os, with a ¹⁸⁷Os/¹⁸⁸Os ratio of 6.95–22.5. The regression of all Re–Os data yields an age of 247 ± 20 Ma, which is within the range of uncertainties of previous Rb–Sr and K–Ar geochronological studies. The scatter in the Re–Os data can be explained in terms of fluctuations in sedimentary conditions, i.e., restricted basin with terrestrial influence.     

The distribution of platinum group elements (PGE) and other chalcophile elements among sulfides from the Creighton Ni–Cu–PGE sulfide deposit, Sudbury, Canada, and the origin of palladium in pentlandite

Concentrations of platinum group elements (PGE), Ag, As, Au, Bi, Cd, Co, Mo, Pb, Re, Sb, Se, Sn, Te, and Zn, have been determined in base metal sulfide (BMS) minerals from the western branch (402 Trough orebodies) of the Creighton Ni–Cu–PGE sulfide deposit, Sudbury, Canada. The sulfide assemblage is dominated by pyrrhotite, with minor pentlandite, chalcopyrite, and pyrite, and they represent monosulfide solid solution (MSS) cumulates. The aim of this study was to establish the distribution of the PGE among the BMS and platinum group minerals (PGM) in order to understand better the petrogenesis of the deposit. Mass balance calculations show that the BMS host all of the Co and Se, a significant proportion (40–90%) of Os, Pd, Ru, Cd, Sn, and Zn, but very little (<35%) of the Ag, Au, Bi, Ir, Mo, Pb, Pt, Rh, Re, Sb, and Te. Osmium and Ru are concentrated in equal proportions in pyrrhotite, pentlandite, and pyrite. Cobalt and Pd (∼1 ppm) are concentrated in pentlandite. Silver, Cd, Sn, Zn, and in rare cases Au and Te, are concentrated in chalcopyrite. Selenium is present in equal proportions in all three BMS. Iridium, Rh, and Pt are present in euhedrally zoned PGE sulfarsenides, which comprise irarsite (IrAsS), hollingworthite (RhAsS), PGE-Ni-rich cobaltite (CoAsS), and subordinate sperrylite (PtAs₂), all of which are hosted predominantly in pyrrhotite and pentlandite. Silver, Au, Bi, Mo, Pb, Re, Sb, and Te are found predominantly in discrete accessory minerals such as electrum (Au–Ag alloy), hessite (Ag₂Te), michenerite (PdBiTe), and rhenium sulfides. The enrichment of Os, Ru, Ni, and Co in pyrrhotite, pentlandite, and pyrite and Ag, Au, Cd, Sn, Te, and Zn in chalcopyrite can be explained by fractional crystallization of MSS from a sulfide liquid followed by exsolution of the sulfides. The early crystallization of the PGE sulfarsenides from the sulfide melt depleted the MSS in Ir and Rh. The bulk of Pd in pentlandite cannot be explained by sulfide fractionation alone because Pd should have partitioned into the residual Cu-rich liquid and be in chalcopyrite or in PGM around chalcopyrite. The variation of Pd among different pentlandite textures provides evidence that Pd diffuses into pentlandite during its exsolution from MSS. The source of Pd was from the small quantity of Pd that partitioned originally into the MSS and a larger quantity of Pd in the nearby Cu-rich portion (intermediate solid solution and/or Pd-bearing PGM). The source of Pd became depleted during the diffusion process, thus later-forming pentlandite (rims of coarse-granular, veinlets, and exsolution flames) contains less Pd than early-forming pentlandite (cores of coarse-granular).     

Comparative study on the geochemical characteristics of rare earth elements in deep-sea sediments from different regions of the Pacific OceanSCIEI北大核心CSCD

太平洋深海沉积物中富集稀土元素(REY,包括钇),被认为是富有潜力的新型稀土资源。(含)沸石粘土、深海粘土和多金属软泥是主要的富含REY的沉积物类型,其中(含)沸石粘土和深海粘土在中、西北太平洋海盆大面积分布,而多金属软泥则多分布于靠近东太平洋洋脊热液活动的深海盆地中。目前关于中、西北太平洋海盆的深海粘土和(含)沸石粘土已有较多的研究,但关于多金属软泥中REY的研究较少。不同区域、不同类型深海沉积物中的稀土元素赋存状态有何差异?影响稀土富集的机制又是什么目前尚不清楚,也就进一步影响了对深海沉积物稀土资源的勘查和开发工作。本文分析对比了太平洋不同区域不同类型深海沉积物的地球化学特征及矿物学特征。结果表明,总体上,中、西北太平洋海盆深海沉积物中,尤其是(含)沸石粘土中的REY含量明显高于东太平洋海盆多金属软泥REY含量,其REY的富集主要与磷酸盐有关。超常富集REY(∑REY>2000×10^(-6))的沉积物中的CaO/P_(2)O_(5)比值趋向于一致(~1.4),几乎接近于磷灰石CaO/P2O5比值(~1.3),因此REY主要赋存载体为磷灰石,该区沉积物中REY的富集可能受到磷酸盐化的影响;东太平洋海盆多金属软泥明显受到热液影响,铁和锰的含量明显增加,但其∑REY含量集中于500×10^(-6)~800×10^(-6),不随铁和锰的增加而变化,REY的富集仍与磷酸盐关系密切,而与铁锰物质和铝硅酸盐关系不大。中、西北太平洋海盆富稀土的深海沉积物形成时处于较强的氧化环境,同时又有充足的含磷物质补给,才造成REY在该区沉积物中的超常富集;而东太平洋海盆多金属软泥虽然处于氧化环境,但缺少足够的磷补给,所以其∑REY含量通常低于中、西北太平洋海盆沸石粘土中∑REY含量。     

Retention of Sm–Nd isotopic ages in garnets subjected to high-grade thermal reworking: implications for diffusion rates of major and rare earth elements and the Sm–Nd closure temperature in garnet

Garnet is a vital mineral for determining constrained P–T–t paths as it can give both the P–T and t information directly. However, estimates of the closure temperature of the Sm–Nd system in garnet vary considerably leading to significant uncertainties in the timing of peak conditions. In this study, five igneous garnets from an early Proterozoic 2414 ± 6 Ma garnet—cordierite bearing s-type granite—which was subjected to high-T reworking have been dated to examine their diffusional behaviour in the Sm–Nd system. Garnets 8, 7, 6 and 2.5 mm in diameter were compositionally profiled and then dated, producing two-point Sm–Nd isochron ages of 2412 ± 10, 2377 ± 5, 2370 ± 5 and 2365 ± 8 and 2313 ± 11 Ma, respectively. A direct correlation exists between grain size and amount of resetting highlighting the effect of grain size on closure temperature. Major element EMPA and LA-ICPMS REE traverses reveal homogenous major element profiles and relict igneous REE profiles. The retention of REE zoning and homogenisation of major element zoning suggest that diffusion rates of REEs are considerably slower than that of the major cations. The retention of REE zoning and the lack of resetting in the largest grains suggest that Sm–Nd closure temperature in garnet is a function of grain size, thermal history and REE zoning in garnet.     

The geochemistry of platinum group elements in marine oil shale—A case study from the Bilong Co oil shale,northern Tibet,China

The Bilong Co oil shale zone is located in the South Qiangtang depression. This zone, together with the Shengli River-Changshe Mountain oil shale zone in the North Qiangtang depression, northern Tibet plateau, represents the potentially largest marine oil shale resource in China. Seventeen samples including oil shale and micritic limestone were collected from the Bilong Co oil shale area to determine the concentrations, distribution patterns, occurrences and origins of platinum group elements (PGEs) in marine oil shale. The oil shale samples from the Bilong Co area exhibit very low total PGE contents ranging from 1.04 to 2.96 ng/g with a weighted mean value of 1.686 ng/g, while the micritic limestone samples from the Bilong Co area exhibit a little lower PGE value ranging from 0.413 to 1.11 ng/g. PGEs in oil shale samples are characterized by high contents in Pd (average 0.79 ng/g), Os (average 0.123 ng/g) and Pt (average 0.644 ng/g) compared with Ru (average 0.068 ng/g), Rh (average 0.033 ng/g) and Ir (average 0.026 ng/g). The highest values for individual PGEs are not uniformly distributed in the section. Clearly, the PGEs are generally enriched in the oil shale samples near the boundary between micritic limestone and oil shale.The individual PGEs in oil shale samples from the Bilong Co area exhibit various modes of occurrence. Ruthenium and Pt occur mainly in pyrite, while Pd is associated mainly with organic matter and Mg-minerals. Rhodium and Os are controlled mainly by pyrite and organic matter. Iridium is present mainly in other Fe-bearing minerals, rather than pyrite. The PGEs in the Bilong Co oil shale are mainly of seawater origin and possibly influenced by terrigenous supply.     

Development characteristics and mechanisms of the Taigu–Qixian earth fissure group in the Taiyuan basin,China

Since the 1980s, increasing human activity and continuing over-exploitation of groundwater resources have caused the earth fissures in the rift basin in Shanxi, China, to enter an active phase. Buildings along these earth fissures have been seriously damaged. Four massive earth fissures that developed in the Taigu and Qixian areas of the eastern Taiyuan basin endanger the operational safety of the high-speed railway that passes through this region. Using field observations, measurements, and exploration, we determined that the four earth fissures are parallel to each other, have a northeast trend, and are separated by approximately equal distances. The rupture zones of these earth fissures are generally 10–50 m wide and are formed by the main fissures and secondary fissures. The width of the zone affected by the earth fissures is 20–50 m based on deformation and the damage done to buildings. These fissures formed on the Earth’s surface; their hanging walls are lower than their foot walls, forming normal faults; and the ground surface around the fissures exhibits ridges and depressions. The fissures are connected to deep hidden faults. The fault displacement increases with increasing depth, which is characteristic of syn-sedimentary faults. These earth fissures are characterized by vertical displacement, and their average annual activity rate is 1–3 cm. We believe that the formation of this large-scale fissure group may be related to the tectonic structure of the hidden faults in the basin and may also be affected by the continuous regional extensional stress of the basin. The current increased level of activity could be caused by the over-exploitation of groundwater in the area.     

Distribution of indium in ores of some base metal and tin–sulfide deposits in Siberia and the Russian Far East

The study of base-metal massive sulfide and tin–sulfide deposits in Siberia and the Russian Far East has revealed that the indium content in ores exceeding the average statistical value at similar deposits worldwide could be economically important. Sphalerite and chalcopyrite and chalcopyrite, bornite, and sphalerite are the major indium carriers in the base-metal massive sulfide and tin–sulfide ores, respectively. In addition, base-metal massive sulfide ores have high Cd, Ag, and Te contents, whereas tin–sulfide ores have elevated Ge, Ga, and Nb contents. This has stimulated the investment attractiveness of these deposits.     

A laser ablation ICP-MS study of platinum-group and chalcophile elements in base metal sulfide minerals of the Jinchuan Ni–Cu sulfide deposit,NW China

The paper presents concentrations of the platinum-group and chalcophile elements in the base metal sulfides (BMS) from the Jinchuan Ni–Cu sulfide deposit determined by laser ablation-inductively coupled plasma-mass spectrometry. Mass balance calculations reveal that pentlandite hosts a large proportion of Co, Ni and Pd (> 65%), and that pentlandite and pyrrhotite accommodate significant proportions of Re, Os, Ru, Rh, and Ag (~ 35–90%), whereas chalcopyrite contains a small amount of Ag (~ 10%) but negligible platinum-group elements. Iridium and Pt are not concentrated in the BMS and mostly occur in As-rich platinum-group minerals. The enrichments of Co, Ni, Re, Os, Ru, and Rh in pentlandite and pyrrhotite, and Cu in chalcopyrite are consistent with the fractionation of sulfide liquid and exsolution of pentlandite and pyrrhotite from the mono-sulfide solid solution (MSS). The Ir-bearing minerals exsolved from the MSS, depleting pentlandite and pyrrhotite in Ir, whereas sperrylite exsolved from the residual sulfide liquid on cooling. Diffusion of Pd from residual sulfide liquid into pentlandite during its exsolution from the MSS and crystallization of Pt-bearing minerals in the residual sulfide liquid resulted in the enrichment of Pd in pentlandite and decoupling between Pd and Pt in the Jinchuan net-textured and massive ores.     

Distribution and fractionation of rare earth elements in soil–water system and human blood and hair from a mining area in southwest Fujian Province,China

Accumulations of rare earth elements (REEs) in human body through multiple pathways including food ingestion, air inhalation and dermal absorption have received considerable attention due to their chronic toxicity to human health. The distribution and fractionation of 14 REEs were conducted in soil, well water, human blood and hair in the vicinity of a large-scale mining site in southwest Fujian Province, China. The LREEs/HREEs ratios were 9.17 for soil, 2.18 for water, 36.93 for human blood and 7.24 for human hair, respectively. The distribution patterns of REEs in soil, human blood and hair samples were characterized by LREEs enrichment and HREEs depletion, but LREEs depletion and HREEs enrichment in water sample. La_N/Yb_N values of these samples ranged from 0.41 to 1.83, La_N/Sm_N values from 0.43 to 4.92, and Gd_N/Yb_N values from 0.81 to 4.71. Soil and human blood showed enrichments of Ce, Gd and Er, but water showed a depletion of Ce. In addition, the normalized patterns showed a weak negative anomaly of Eu in soil and a weak negative anomaly of Nd in human blood and hair. Consequently, enrichment and depletion of REEs differ significantly among soil, water and human blood and hair, thus the REEs after entering into human body can undergo fractionation effects.