矿区周边地下水中重金属纳米微粒污染物的潜在危害

纳米科学技术的飞速发展使得纳米物质的生态环境危害受到了广泛关注,重金属纳米微粒尤甚,而在现行的地下水重金属污染的评估体系中,金属元素浓度的高低是主要的评判标准,如《中华人民共和国生活饮用水卫生标准》(GB5749—2006)中明确规定了饮用水中Pb、Zn、Cu、Ag、Cr、Hg等多个金属元素的浓度限值。

湖南鸭公塘铜铅锌硫多金属矿床地下水纳米微粒特征研究

以湖南省鸭公塘铜铅锌硫多金属隐伏矿床地下水样品为研究对象,并选取广东省肇庆市白土盆地的地下水作为背景样,利用透射电镜(TEM)原位液体芯片观察到地下水纳米微粒的原始状态,再分析它们的元素种类、组合及比值等特征。分析结果表明:地下水纳米微粒常以单颗粒(粒度为50~500 nm)和聚合体两种形式存在,并以聚合体为主。其中矿床地下水微粒主要含有Ag、Cu、Fe、Pb、Zn等元素,元素组合形式主要有Zn-Cu-Fe、PbFe-Cu、Pb-Cu-Zn等,与矿床成矿元素组合一致。背景区地下水纳米微粒主要含有地壳常见元素,元素组合未见异常。通过对比两地地下水纳米微粒特征可知,矿床地下水含金属纳米微粒与深部隐伏矿体关系密切。此外,所捕获的矿床地下水纳米微粒多具有形态方面棱角分明、组成物质中金属硫酸盐含量高且金属氧化物价态高等现象,结合该矿区断层发育的特点,推测断层作用和氧化作用是鸭公塘矿床地下水纳米微粒形成的主要方式。由于纳米微粒能通过载体地下水迁移,并能很好地反映隐伏矿体信息,说明通过地下水纳米微粒特征探测隐伏矿体是可行的,对于深部资源探测具有指示意义。

Geochronology and Geochemistry of Mafic Dikes from Hainan Island and Tectonic Implications

In the present study, the major and trace element compositions, as well as Sr, Nd isotopic compositions and K-Ar age data in mafic dikes from Hainan Island, China, have been analyzed. Whole-rock K-Ar dating yielded a magmatic duration of 61-98 Ma for mafic dikes. Mafic dikes have a very high concentration of incompatible elements, for example, Ba, Rb, Sr, K, rare earth elements, and especially light rare earth elements （LREE）, and negative anomalies of Nb, Ta, and Ti in the normalized trace element patterns. The initial 87Sr/86Sr ratios and εSr（t） of the mafic dikes are 0.70634- 0.71193 and ＋27.7 to ＋112.2, respectively. In the 87Sr/86Sr versus εNd（t） diagram, the Hainan Island mafic dikes plot between fields for depleted mantle and enriched mantle type 2. All these characteristics show that the mantle （source region） of mafic dikes in this area experienced metasomatism by fluids relatively enriched in LREE and large ion lithophUe elements. The genesis of Hainan Island mafic dikes is explained as a result of the mixing of asthenospheric mantle with lithospheric mantle that experienced metasomatism by the subduction of the Pacific Plate. This is different from the Hainan Island Cenozoic basalts mainly derived from depleted asthenospheric mantle, and possibly, minor metasomatised lithospheric mantle. This study suggests that the Mesozoic and Cenozoic lithospheric revolutions in Hainan Island can be divided into three stages： （1） the compression orogenesis stage before 98 Ma. The dominant factor during this stage is the subduction of the ancient Pacific Plate beneath this area. The lithospheric mantle changed into enriched mantle type 2 by metasomatism; （2） the thinning and extension stage during 61-98 Ma. The dominant factor during this stage is that the asthenospheric mantle invaded and corroded the lithospheric mantle; and （3） the large-scale thinning and extension stage after 61 Ma. The large-scale asthenospheric upwelling results in the strong erupting of Cenozoic basalts, large-scale thinning of the lithosphere, the southward translating and counterclockwise rotating of Hainan Island, and the opening of the South China Sea.

内蒙古扎木敖包矿床土壤气体纳米微粒特征研究

以内蒙古戈壁地区扎木敖包矿床为研究对象,采用透射电镜研究该矿床土壤气体纳米微粒的形貌、化学成分、大小、结构、聚合等特征,旨在克服该地区厚砂砾层的屏蔽作用探查深部隐伏矿体。结果表明:微粒兼具有聚合体和单一颗粒形态,多以聚合体形态出现,粒度为30~550 nm,形态各异,多数为多晶。微粒的主要金属成分为Fe、Pb、Zn、Cu、Sn、Mo等,多见Fe-Zn、Pb-Fe-Zn的组合方式,这些特征与矿体金属矿物元素种类和组合特征对应性良好。含Fe微粒对金属元素具有良好的吸附能力,Zn元素多见被吸附而携带迁移。对比背景区微粒成分同地层成分相似的情况,矿区微粒的成矿元素异常指示其与深部矿体具有密切联系。微粒的成分包括氧化物、氢氧化物、硫酸盐等,含氧量普遍偏高,金属元素及S元素多以高价态形式存在,结合地貌和断层发育特点,推测扎木敖包纳米微粒的成因为氧化作用或断层加后期氧化作用。

卡休他他矿床地下水纳米微粒特征及意义

采集内蒙古卡休他他矿区附近的地下水微粒进行相关分析,同时也采集远离矿区的井水微粒作为对照,利用高分辨率透射电镜对这些微粒进行单颗粒纳米微粒分析,研究表明:卡休他他矿床地下水中的异常金属微粒主要为含Fe、Cu、Zn微粒,含Zn、Cu微粒原子百分含量分别可达80.3%、22.7%,而背景区井水样品中无Ag、Cu微粒,且矿区地下水中与成矿相关的金属元素含量大大高于井水;含金属微粒与深部矿体成分(磁铁矿、黄铁矿、闪锌矿、黄铜矿等)具有很好的对应性,表明了矿区地下水含金属微粒来自于深部矿体,能携带深部矿体的信息,这为深部隐伏矿体的勘探提供了思路,也能为今后同类型的矿床勘探提供一定的参考.此外,本次研究还表明矿区附近的地下水可能受到了成矿微粒的影响,这可能也会影响到地下饮用水的品质,地下水含金属微粒研究方法也可用于检测地下饮用水的污染.

Particles carried by ascending gas flow at the Tongchanghe copper mine,Guizhou Province,China

We collected and analyzed, using transmission electron microscopy, the particles carried by ascending gas flow in soil above the concealed orebody of the Tongchanghe copper mine, Guizhou Province. Particles of native copper, native copper-iron alloy, and native chromium-iron-copper alloy particles in the ascending gas flow were first discovered. Commonly, they were aggre- gations of relatively small particles. Individual particles within aggregations were subcircular, elliptical, regularly polygonal, or elongate and from 5 to 40 nm in size. The aggregations were subcircular or elliptical and 20-150 nm in size. Chloride, oxide, sulfate, and hydroxide particles containing ore-forming metals in the ascending gas flow were also discovered. The elements of the particles were commonly in a high valence state, suggesting that they were formed in a near-surface oxidizing environment. Discovery of the particles extracted from the ascending gas flow above the Tongchanghe copper mineprovided a powerful tool for exploration for deep concealed orebodies. Our study also showed that native copper, native copper-iron alloys, native chromium-iron-copper alloys, as well as chloride, oxide, sulfate, and hydroxide compounds containing ore-forming metals can be transported in particle form by ascending gas flow below the Earth's surface.

云南小寨铜矿苏家箐矿段地气微粒特征

针对云南小寨铜矿苏家箐矿段地气采样所获得的16个地气微粒样品进行透射电镜观察分析,结果表明:地气中微粒呈现纳米级,大小为10nm到300nm不等,多为微粒聚合体,单体较少。微粒的形状多样,有似六边形、似椭球状、球状、不规则状等。微粒中含有成矿元素Cu以及伴生元素Fe,Pb,Zn,Mn,Co等,如SJQ-2A微粒中Pb含量为62.9%,SJQ-5B微粒中Co含量为24.1%。Cu出现频次很高,其质量分数也较高,如SJQ-1B和SJQ-6微粒中Cu含量分别为64.0%和73.3%。推测含金属微粒来源于深部隐伏矿体,金属微粒含有丰富的矿体信息。通过对比7个不同矿床的地气微粒特征,发现矿床类型不同其微粒特征(如种类、成分、形态、大小等)有较大差异;而与小寨铜矿苏家箐矿段具有相似地质环境的矿床,其地气微粒特征具有较大的相似性。微粒的元素组成与地下深处矿体具有较好的对应关系,无疑对该矿区今后的地质找矿具有指导意义。