重砂分级-扫描电镜-能谱等技术研究湖南张家界黑色页岩贵金属元素赋存状态     

周姣花  周晶  牛睿  徐畅 《岩矿测试》2019,38(6):649-659

黑色岩系是多种有用元素的重要载体,Cu、Pb、Zn、Ni、Mo、V、U、Au、Ag、稀有和稀土元素在黑色岩系中异常富集,某些黑色岩系的贵金属(铂族元素、Au、Ag)也异常富集,其含量甚至部分超过了基性和超基性岩,这类黑色页岩矿床中铂族元素(PGEs)的赋存状态至今尚未有一个确切的定论。本文采集了湖南张家界属寒武系牛蹄塘组黑色页岩中Mo-Ni矿层作为研究样品,通过化学分析表明矿石中含Pt 531×10~(-9),Pd 514×10~(-9),Os 185×10~(-9),PGEs合量为1259.43×10~(-9),Au 332×10~(-9),Ag 12.2×10~(-6),已富集成矿。进一步利用重砂分级、化学分析、X射线衍射、扫描电镜及能谱技术研究了贵金属元素赋存状态,结果表明:①Ag:主要以独立矿物形式存在,少量以类质同象形式赋存在其他矿物中。独立矿物有砷铜银矿、硫锑铜银矿、硫锑铅银矿、锑银矿、硫银锡矿、硫砷银铅矿、银黄锡矿、辉银矿、锑-银-锡互化物;类质同象主要是银黝铜矿-银砷黝铜矿、含银方铅矿和含银砷铜矿等。②Au:未发现独立矿物,黄铁矿是重要载金矿物。③PGEs:未见独立矿物,在不同重砂分级样品中没有富集,具分散性,推测铂族矿物很可能是以纳米形式存在,建议今后研究选矿工艺时,可考虑从制取纳米材料的思路进行应用研究。本文Ag-Sn-Sb互化物的发现为研究黑色岩系多元素富集成因机制提供了重要物证。  相似文献   

Experimental investigation on thermochemical sulfate reduction in the presence of 1-pentanethiol at 200 and 250 °C: Implications for in situ TSR processes occurring in some MVT deposits     

《Ore Geology Reviews》2017

Organic sulfur compounds are ubiquitous in natural oil and gas fields and moderate-low temperature sulfide ore deposits. Previous studies have shown that organic sulfur compounds are important in enhancing the rates of thermochemical sulfate reduction (TSR) reactions, but the details of these reaction mechanisms remain unclear. In order to assess the extent of sulfate reduction in the presence of labile sulfur species at temperature conditions near to those where TSR occurs in nature, we conducted a series of experiments using the fused silica capillary capsule (FCSS) method. The tested systems containing labile sulfur species are MgSO₄ + 1-pentanethiol (C₅H₁₁SH) + 1-octene (C₈H₁₆), MgSO₄ + 1-octene (C₈H₁₆), MgSO₄ + 1-pentanethiol (C₅H₁₁SH), 1-pentanethiol (C₅H₁₁SH)+H₂O, and MgSO₄ + 1-pentanethiol (C₅H₁₁SH) + ZnBr₂ systems. Our results show that: (1) intermediate oxidized carbon species (ethanol and acetic acid) are formed during TSR simulation experiments when 1-pentanethiol is present; (2) in the presence of ZnBr₂, 1-pentanethiol can be oxidized by sulfate to CO₂ at 200 °C, which is within the temperature range observed in natural TSR; and (3) the precipitation of sulfide minerals may significantly promote the rate of TSR, indicating that the rates of in situ TSR reactions in ore deposits could be much faster than previously thought. This may be important for understanding the possibility of in situ TSR as a mechanism for the precipitation of metal sulfides in some ore deposits. These findings provide important experimental evidence for understanding the role of organic sulfur compounds in TSR reactions and the pathway of TSR reactions initiated by organic sulfur compounds under natural conditions.  相似文献   

Organochlorine contamination (PCBs, DDTs, HCB, HCHs) in sediments from Cienfuegos bay, Cuba   总被引：1，自引：0，他引：1  

I. Tolosa  M. Mesa-Albernas 《Marine pollution bulletin》2010,60(9):1619-1624

The spatial distribution of various organochlorinated compounds, e.g. PCBs, DDTs, HCB and HCHs, were investigated in sediments from Cienfuegos bay, Cuba. Their concentrations appeared to be relatively low by global standards and only sediments receiving the impact from the residual waters of the city and thermoelectrical power approached the sediment quality guidelines for PCBs and DDTs. Relatively higher ΣDDT concentrations and high DDT/DDE + DDD ratios in two sites near the outfalls of the city indicated a current DDT usage, probably linked to public health emergencies. These results contribute to the sparse regional database for organochlorinated compounds in the Caribbean marine environment.  相似文献   

Distribution of petroleum hydrocarbons and organochlorinated contaminants in marine biota and coastal sediments from the ROPME Sea Area during 2005   总被引：3，自引：0，他引：3  

de Mora S  Tolosa I  Fowler SW  Villeneuve JP  Cassi R  Cattini C 《Marine pollution bulletin》2010,60(12):2323-2349

The composition and spatial distribution of various petroleum hydrocarbons (PHs), comprising both aliphatic and polycyclic aromatic hydrocarbons (PAHs), and selected chlorinated pesticides and PCBs were measured in biota and coastal sediments from seven countries in the Persian Gulf and the Gulf of Oman (Bahrain, Iran, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates). Evidence of extensive marine contamination with respect to organochlorinated compounds and PHs was not observed. Only one site, namely the BAPCO oil refinery in Bahrain, was considered to be chronically contaminated. Comparison of the results from this survey for Σ DDTs and Σ PCBs in rock oysters from the Gulf of Oman with similar measurements made at the same locations over the past two decades indicates a temporal trend of overall decreasing Σ PCB concentrations in oysters, whereas Σ DDTs levels have little changed during that period.  相似文献   

天津地区典型土壤剖面多环芳烃的垂向分布特征   总被引：18，自引：4，他引：14  

张枝焕  王学军  陶澍  彭正琼  崔艳红  吴水平  叶必雄  苑金鹏 《地理科学》2004,24(5):562-567

天津地区不同环境功能区表层土中均检出萘、苊、苊烯、联苯、菲、惹烯、芴、二苯并呋喃、二苯并噻吩、荧蒽、芘、屈、苯并芴、苯并蒽、苯并荧蒽、苯并芘、、二苯并[a,h]蒽、茚并[1,2,3-cd]芘、苯并[g,h,i]等多环芳烃化合物,但含量差别显著,南、北排污河污灌区多环芳烃含量明显高于非污染区及北部山区。不同剖面表土中多环芳烃的组成特征也存在明显差别,与非污灌耕地及北部山地相比,污灌耕地和滨海盐土耕地四环以上芳烃相对含量明显较高,而烷基取代物含量明显较低。剖面表层至40cm土壤中多环芳烃含量相对较高,深处含量明显降低,但不同剖面变化幅度存在明显差别,污灌耕地和滨海盐土耕地降低幅度最大,其它剖面变化较小,但剖面深部(>40cm)芳烃化合物组成特征基本趋于一致。  相似文献   

氨化学电离色谱-质谱法分析原油及岩石抽提物中的咔唑类含氮化合物     

史权  朱雷  朱丹  王春江  王铁冠 《地球化学》2004,33(4):395-399

利用色谱氨化学电离质谱(GC-NH3CIMS)法分析了原油及烃源岩中的咔唑类含氮化合物,分析结果与普通色谱质谱(GC-MS)进行了对比与评价.结果表明,氨化学电离质谱法对含氮化合物具有较高的灵敏度和选择性,在氮化物含量较低或有芳烃共逸出的情况下,可以进行定量分析.氨化学电离质谱没有碎片离子产生,质量色谱图上同系物间没有碎片离子产生的相互干扰,定量结果比较准确.  相似文献   

Biogenic Volatile Organic Compounds (VOC): An Overview on Emission, Physiology and Ecology   总被引：50，自引：0，他引：50  

J. Kesselmeier  M. Staudt 《Journal of Atmospheric Chemistry》1999,33(1):23-88

This overview compiles the actual knowledge of the biogenic emissions of some volatile organic compounds (VOCs), i.e., isoprene, terpenes, alkanes, alkenes, alcohols, esters, carbonyls, and acids. We discuss VOC biosynthesis, emission inventories, relations between emission and plant physiology as well as temperature and radiation, and ecophysiological functions. For isoprene and monoterpenes, an extended summary of standard emission factors, with data related to the plant genus and species, is included. The data compilation shows that we have quite a substantial knowledge of the emission of isoprene and monoterpenes, including emission rates, emission regulation, and biosynthesis. The situation is worse in the case of numerous other compounds (other VOCs or OVOCs) being emitted by the biosphere. This is reflected in the insufficient knowledge of emission rates and biological functions. Except for the terpenoids, only a limited number of studies of OVOCs are available; data are summarized for alkanes, alkenes, carbonyls, alcohols, acids, and esters. In addition to closing these gaps of knowledge, one of the major objectives for future VOC research is improving our knowledge of the fate of organic carbon in the atmosphere, ending up in oxidation products and/or as aerosol particles.  相似文献   

Hydrodynamic loads on subsea robots     

Carlos Rivera  Michael Hinchey 《Ocean Engineering》1999,26(8):589

Free floating subsea robots are often subjected to complex hydrodynamic loads due to waves/currents and wakes from nearby structures. This makes control extremely difficult. Good hydrodynamics data might counteract this. This paper presents hydrodynamics data for two configurations undergoing various combinations of steady translation and approximately steady rotation. The two configurations are: a spherical body with a single fixed link arm and a two link arm without a body. For both configurations neural networks were found to provide a reasonable fit to the data. We believe that such fits could be used to improve control.  相似文献   

Methane gas Seeps Along the Oxic/Anoxic Gradient in the Black Sea: Manifestations, Biogenic Sediment Compounds and Preliminary Results on Benthic Ecology   总被引：2，自引：0，他引：2  

Claudia Luth  Ulf Luth  Audrey V. Gebruk  &Hjalmar Thiel 《Marine Ecology》1999,20(3-4):221-249

Abstract. Sediment parameters (grain size, organic content, chloroplastic pigments, Adenylates, Potential hydrolytic activity and electron transport system activity) and benthic biota were studied in methane seep area south-west of the Crimean Peninsula in the Black Sea over a depth range from 60 to 260m. A control transect with similar depths was performed in an adjacent nonseep area. Methane seepage in this region occurs from 35 to ˜ 85m depth, passing the oxic anoxic interface zone at 130 to 180m. The methane seep areas were characterized by abundant carbonate precipitates which occurred in various shapes from small, flat structures to tall chimneys with increasing anoxia. The carbonates were associated with distinct bacterial mats. Most of the measured biochemical parameters in the sediment were quite similar in the seep and nonseep areas. The content of organic matter was higher and grain size was more uniform in the nonseep areas. However, the seep areas were charaterized by highter proportions of the larger fauna (size classes 0.5–1 mm and ≥ 1mm) as well as increased total numbers of benthic fauna in the suboxic and upper anoxic zone. The animals did not show any seep-specific adaptations. In addition to methane seepage, highly variable hydrochemical and sedimentary conditions on the lower shelf and upper slope may also play an important role in structuring the composition and distribution of the benthic fauna.  相似文献   

南极布兰斯菲尔德海峡表层沉积物烷基芳烃化合物     

卢冰  唐运千  眭良仁  厉善华 《海洋学报》1999,21(2):124-133

芳烃化合物广泛分布于沉积物(古老和现代)、石油和煤炭中,它与沉积有机质的演化与成熟度有着密切的关系,如二甲基素的相对丰度变化,反映了有关沉积物成熟度的信息;又如二甲基带与三甲基察的相对丰度可作为原油成熟度的标志,它优于以生物标志物作为依据的指标[1].  相似文献