恩施地区土壤与农作物硒镉地球化学特征

恩施州已开展的1∶25万土地地球化学调查结果显示,恩施地区表层土壤中硒含量丰富,但镉含量同样较高。笔者以该地区3 950件表层土壤及362件作物硒、镉等含量指标为基础,讨论了硒、镉元素地球化学特征,共生成因以及不同种类作物对两种元素的吸收富集能力。结果表明,土壤中硒、镉呈伴生关系,含量分布主要受控于该地区二叠系发育的黑色岩系成土母质,赋存状态与土壤中的有机质和硫化物密切相关。不同作物生物富集系数对比结果显示,银杏、玉米和茶叶对硒的吸收能力高于镉,可作为恩施地区富硒农产品开发的优选作物,同时还应考虑土壤的pH值,中碱性土壤农产品镉富集风险较低。此外,硒对于镉有解毒作用,高硒环境将会显著降低镉对人体的健康风险。     

湖北恩施首次发现硒超富集植物

湖北恩施地区富硒的二叠系炭质硅质岩和炭质页岩(石煤)岩层广泛出露地表,风化淋滤造就了恩施地区富硒的环境,20世纪60年代曾经爆发了世界上首例人群硒中毒事件,迫使渔塘坝居民整体搬迁.     

湖北恩施天然富硒豆角中发现抗癌硒化合物

<正>硒是一种人体必需的微量元素,在人体内充当多种含硒酶,如谷胱甘肽过氧化酶的活动中心,保护细胞膜免受氧自由基氧化损失的作用,某些特殊形态的硒化合物能抑制癌症肿瘤的生长,具有防癌抗癌的特殊效应。我国湖北恩施地区是世界上典型的高硒地球化学背景区,不仅蕴藏有丰富的硒矿地质资源,还发育大量的富硒植物资源,是开发富硒食品及医药保健品的理想基地。其中恩施州建始县安乐井村种植的天然绿色豆角(Passeolus Vulagaris),其总硒含量测定结果为38.20     

湖北恩施硒中毒区土壤硒的分布及其控制因素

将湖北恩施地区高硒环境的土壤划分为（1）高总硒高水溶性硒，（2）低总硒高水溶性硒，（3）低总硒低水溶性硒。前两种类型可定义为高硒中毒危险区土壤，后一种类型为非中毒区正常土壤这种分类便于对高危险区的预测和制定预防措施，控制高硒区不同类型分布的因素主要有土壤母质和出露的岩石型、产状。     

承德市富硒土壤区镉的地球化学特征及生态风险评价

硒是人体必需的生命元素,开发富硒农产品是提升人体硒摄入的安全有效途径,富硒土地资源是开发富硒农产品的基础。然而,近年来全国开展的多目标地球化学调查发现,富硒土壤中重金属元素镉通常较高,不利于富硒土地开发利用,因此,研究富硒土壤区镉的地球化学特征和生态风险状况对于富硒土地开发具有重要的指导意义。文章对承德市富硒土壤区表层土壤中主要的重金属元素镉的地球化学特征及生态风险进行评价,旨在为承德市富硒土地开发利用提供科学依据。采用“七步提取法”研究了表层土壤镉的形态特征。同时,配套分析了苹果、玉米样品中的重金属元素镉的含量,以了解其生物有效性。结果显示:承德市富硒土壤区表层土壤镉在全区均较富集,在新积土和中性粗骨土、水田中显著富集。研究区圈定了4处镉轻度污染土壤,均在表层土壤镉的高值区。表层土壤镉形态平均含量大小顺序为:水溶态 < 离子交换态 < 强有机结合态 < 腐殖酸结合态 < 铁锰氧化物结合态 < 碳酸盐结合态 < 残渣态,生态风险相对较低。表层土壤镉未对苹果和玉米样品产生影响,苹果和玉米中镉均不超标。承德市富硒土壤区表层土壤镉的生态风险较低,暂不影响承德市富硒土地开发利用。     

魅力硒都 云蒸霞蔚的山与水——湖北恩施大峡谷

硒是人与动物不可缺少的微量元素之一,被称为点燃人类健康的＂生命火种＂,有效地摄入硒,可以防治多种疾病的发生。湖北恩施是迄今为止＂全球唯一探明独立硒矿床＂所在地,境内硒矿蕴藏量居世界第一,还是世界天然生物硒资源最富集的地区,被誉为＂世界硒都＂。恩施市境内由富硒土壤、富硒山泉水、富硒动植物资源聚集形成了天然富硒生物圈,在这里生长的植物、动物、微生物等,它们的硒含量明显高于世界上其他地区的同类物种。上世纪60年代,恩施市发现硒矿。     

湖北省富硒资源的地质特征及利用区划

在系统收集并综合相关成果资料的基础上,结合野外典型区域样品的采集和补充,全面分析了湖北省不同类型硒资源地质特征,并对其利用区划进行了探讨。研究表明:湖北省富硒地层主要有寒武系(32.1%)、二叠系(29.8%)及震旦系(25.8%);富硒岩石主要为炭质页岩、炭质板岩、硅质岩、炭质硅质岩和含炭页岩;表层富硒土壤主要分布于江汉平原区、恩施地区和鄂东南地区。主要为湖积、冲积成因。恩施地区的高硒和极高硒土壤与二叠系富硒地层及双河硒矿点和矿化点的分布相吻合。鄂东南地区富硒土壤一方面与二叠系地层有关,另一方面与鄂东南地区硒的伴生矿床有关。     

恩施富硒豆角中硒的形态研究

<正>硒是一种人体必需的微量元素,在人体内充当多种含硒酶,如谷胱甘肽过氧化酶的活动中心等,保护细胞膜免受氧自由基氧化损失的作用,具有防癌抗癌的生物化学功能。硒甲基半胱氨酸及其衍生物γ-谷氨酰硒甲基半胱氨酸是国际上公认的具有抗癌效应的机硒化物(Ip et al.,2000;Stan et al.,2008),富硒食品中是否富含这两种特殊的有机硒,关系此富硒食品有无抗癌防癌的功效。我国湖北恩施地区     

西南寒武、二叠系富硒碳质岩中硒结合态的比较研究

使用硒的7步连续化学提取技术,对采自贵州寒武纪牛蹄塘组和湖北恩施二叠纪茅口组富硒碳质岩中的水溶态、可交换态、有机态、元素态、酸性提取态、硫化物/硒化物态和残渣态硒进行了比较研究,应用氢化物－原子荧光法测定了岩石总硒和各结合态硒。结果表明,恩施二叠纪沙地新鲜富硒碳质硅质岩和碳质页岩中的硒主要以有机结合态和硫化物/硒化物态硒为主,残渣态硒较低;遵义松林早寒武世碳质硅质岩中的硒主要以有机结合态和硫化物态硒为主,碳质页岩与镍钼矿层中则以有机结合态、残渣态和硫化物态硒为主,斑脱岩中主要以有机结合态、元素态和可交换态硒为主。根据硒结合态的这种分布特征,推测二叠纪、寒武纪富硒碳质岩中硒初始富集的生物地球化学过程略有差异：前者碳质硅质岩中主要以微生物还原为主,碳质页岩中则是微生物还原作用和生物同化吸收或吸附兼而有之;后者主要以生物同化吸收或吸附为主,微生物还原次之。     

植物对硒的利用过程及其机制

<正>硒是人体和动物必须的微量元素,具有防癌、抗衰老、抗氧化等多种生物学功能。世界上绝大多数地区属于缺硒地区,我国约有72%的地区不同程度缺硒。然而,硒过量地区又可能发生人群硒中毒事件。因此,硒与人体健康状况关系密切。前期研究表明,人体对植物硒的摄入是硒进入人体的主要途径[1]。然而,植物对硒的吸收、利用、转化过程及其机制的研究仍比较缺乏。本研究选取典型高硒区湖北恩施生长的富硒植物壶瓶碎米荠(C.hupingshanesis)为研究对象,利用基于同步时辐射X射线吸收精细结构谱技术(XAFS)     

Isotopic systematics of He,Ar, S,Cu, Ni,Re, Os,Pb, U,Sm, Nd,Rb, Sr,Lu, and Hf in the rocks and ores of the Norilsk deposits

This paper reports the first results of a study of 11 isotope systems (³He/⁴He, ⁴⁰Ar/³⁶Ar, ³⁴S/³²S, ⁶⁵Cu/⁶³Cu, ⁶²Ni/⁶⁰Ni, ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, ^206–208Pb/²⁰⁴Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others.     

高压微波消解法测定醋酸纤维过滤器采集的微尘粒子中的砷镉钴铬铜铁锰镍铅钒锌

最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提     

Wavelength-dispersive X-ray fluorescence spectrometric determination of Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites

Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours.     

Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA

The Kuskokwim River at Bethel, Alaska, drains a major mercury-antimony metallogenic province in its upper reaches and tributaries. Bethel (population 4000) is situated on the Kuskokwim floodplain and also draws its water supply from wells located in river-deposited sediment. A boring through overbank and floodplain sediment has provided material to establish a baseline datum for sediment-hosted heavy metals. Mercury (total), arsenic, antimony, and selenium contents were determined; aluminum was also determined and used as normalizing factor. The contents of the heavy metals were relatively constant with depth and do not reflect any potential enrichment from upstream contaminant sources.     

Roles of xenomelts,xenoliths, xenocrysts,xenovolatiles, residues,and skarns in the genesis,transport, and localization of magmatic Fe-Ni-Cu-PGE sulfides and chromite

Most sulfide-rich magmatic Ni-Cu-(PGE) deposits form in dynamic magmatic systems by partial melting S-bearing wall rocks with variable degrees of assimilation of miscible silicate and volatile components, and generation of barren to weakly-mineralized immiscible Fe sulfide xenomelts into which Ni-Cu-Co-PGE partition from the magma. Some exceptionally-thick magmatic Cr deposits may form by partial melting oxide-bearing wall rocks with variable degrees of assimilation of the miscible silicate and volatile components, and generation of barren Fe ± Ti oxide xenocrysts into which Cr-Mg-V ± Ti partition from the magma. The products of these processes are variably preserved as skarns, residues, xenoliths, xenocrysts, xenomelts, and xenovolatiles, which play important to critical roles in ore genesis, transport, localization, and/or modification. Incorporation of barren xenoliths/autoliths may induce small amounts of sulfide/chromite to segregate, but incorporation of sulfide xenomelts or oxide xenocrysts with dynamic upgrading of metal tenors (PGE > Cu > Ni > Co and Cr > V > Ti, respectively) is required to make significant ore deposits. Silicate xenomelts are only rarely preserved, but will be variably depleted in chalcophile and ferrous metals. Less dense felsic xenoliths may aid upward sulfide transport by increasing the effective viscosity and decreasing the bulk density of the magma. Denser mafic or metamorphosed xenoliths may also increase the effective viscosity of the magma, but may aid downward sulfide transport by increasing the bulk density of the magma. Sulfide wets olivine, so olivine xenocrysts may act as filter beds to collect advected finely dispersed sulfide droplets, but other silicates and xenoliths may not be wetted by sulfides. Xenovolatiles may retard settling of – or in some cases float – dense sulfide droplets. Reactions of sulfide melts with felsic country rocks may generate Fe-rich skarns that may allow sulfide melts to fractionate to more extreme Cu-Ni-rich compositions. Xenoliths, xenocrysts, xenomelts, and xenovolatiles are more likely to be preserved in cooler basaltic magmas than in hotter komatiitic magmas, and are more likely to be preserved in less dynamic (less turbulent) systems/domain/phases than in more dynamic (more turbulent) systems/domains/phases. Massive to semi-massive Ni-Cu-PGE and Cr mineralization and xenoliths are often localized within footwall embayments, dilations/jogs in dikes, throats of magma conduits, and the horizontal segments of dike-chonolith and dike-sill complexes, which represent fluid dynamic traps for both ascending and descending sulfides/oxides. If skarns, residues, xenoliths, xenocrysts, xenomelts, and/or xenovolatiles are present, they provide important constraints on ore genesis and they are valuable exploration indicators, but they must be included in elemental and isotopic mass balance calculations.     

Regional distribution of Al,B, Ba,Ca, K,La, Mg,Mn, Na,P, Rb,Si, Sr,Th, U and Y in terrestrial moss within a 188,000 km2 area of the central Barents region: influence of geology,seaspray and human activity

Five hundred and ninety-eight samples of terrestrial moss (Hylocomium splendens and Pleurozium schreberi) collected from a 188,000 km² area of the central Barents region (NE Norway, N Finland, NW Russia) were analysed by ICP-AES and ICP-MS. Analytical results for Al, B, Ba, Ca, K, La, Mg, Mn, Na, P, Rb, Si, Sr, Th, U and Y concentrations are reported here. Graphical methods of data analysis, such as geochemical maps, cumulative frequency diagrams, boxplots and scatterplots, are used to interpret the origin of the patterns for these elements. None of the elements reported here are emitted in significant amounts from the smelting industry on the Kola Peninsula. Despite the conventional view that moss chemistry reflects atmospheric element input, the nature of the underlying mineral substrate (regolith or bedrock) is found to have a considerable influence on moss composition for several elements. This influence of the chemistry of the mineral substrate can take place in a variety of ways. (1) It can be completely natural, reflecting the ability of higher plants to take up elements from deep soil horizons and shed them with litterfall onto the surface. (2) It can result from naturally increased soil dust input where vegetation is scarce due to harsh climatic conditions for instance. Alternatively, substrate influence can be enhanced by human activity, such as open-cast mining, creation of ‘technogenic deserts’, or handling, transport and storage of ore and ore products, all of which magnify the natural elemental flux from bedrock to ground vegetation. Seaspray is another natural process affecting moss composition in the area (Mg, Na), and this is most visible in the Norwegian part of the study area. Presence or absence of some plant species, e.g., lichens, seems to influence moss chemistry. This is shown by the low concentrations of B or K in moss on the Finnish and Norwegian side of the (fenced) border with Russia, contrasting with high concentrations on the other side (intensive reindeer husbandry west of the border has selectively depleted the lichen population).     

Petrographic, mineralogy, and geochemistry of coals of Pabedana, Kerman Province, Central Iran

This paper discusses the result of the detailed investigations carried out on the coal characteristics, including coal petrography and its geochemistry of the Pabedana region. A total of 16 samples were collected from four coal seams d2, d4, d5, and d6 of the Pabedana underground mine which is located in the central part of the Central-East Iranian Microcontinent. These samples were reduced to four samples through composite sampling of each seam and were analyzed for their petrographic, mineralogical, and geochemical compositions. Proximate analysis data of the Pabedana coals indicate no major variations in the moisture, ash, volatile matter, and fixed carbon contents in the coals of different seams. Based on sulfur content, the Pabedana coals may be classified as low-sulfur coals. The low-sulfur contents in the Pabedana coal and relatively low proportion of pyritic sulfur suggest a possible fresh water environment during the deposition of the peat of the Pabedana coal. X-ray diffraction and petrographic analyses indicate the presence of pyrite in coal samples. The Pabedana coals have been classified as a high volatile, bituminous coal in accordance with the vitrinite reflectance values (58.75–74.32 %) and other rank parameters (carbon, calorific value, and volatile matter content). The maceral analysis and reflectance study suggest that the coals in all the four seams are of good quality with low maceral matter association. Mineralogical investigations indicate that the inorganic fraction in the Pabedana coal samples is dominated by carbonates; thus, constituting the major inorganic fraction of the coal samples. Illite, kaolinite, muscovite, quartz, feldspar, apatite, and hematite occur as minor or trace phases. The variation in major elements content is relatively narrow between different coal seams. Elements Sc,, Zr, Ga, Ge, La, As, W, Ce, Sb, Nb, Th, Pb, Se, Tl, Bi, Hg, Re, Li, Zn, Mo, and Ba show varying negative correlation with ash yield. These elements possibly have an organic affinity and may be present as primary biological concentrations either with tissues in living condition and/or through sorption and formation of organometallic compounds.