华南含钨建造的地球化学研究

通过对华南代表性的地层地球化学研究,证实了华南成矿区域中合钨建造的存在。目前已确立的含钨建造主要有元古界、寒武系、泥盆系和石炭系。钨在不同构造带及不同时代含钨建造中的含量各有不同,但共同的地球化学特点是钨的丰度较高,具有一定的微量元素组合和分布型式。钨在含钨建造中的初步富集为华南地区钨的大规模、多样性的矿化奠定了物质基础。     

云南晋宁梅树村前寒武系—寒武系界线剖面的磁性地层学研究

本文在晋宁梅树村的前寒武系—寒武系剖面上,较系统地在53个采点上采集了112块岩心标本(249块样品)。磁性地层学研究指出该剖面中一些极性混合带与小壳动物化石群的出现与衰亡的时空位置吻合,反映了地磁场倒转与小壳动物化石群演化的相关性。古纬度信息表明中谊村段主要磷矿层位正是低纬度带控制的古地理环境,文章为晚前寒武纪—寒武纪磁性地层序列研究提供了实际资料。     

浙江绍兴-龙泉隆起带前中生界含金建造的地球化学

本文对浙江绍兴-龙泉隆起带中主要金矿床的围岩进行了系统的地球化学研究,确定了该区存在有前中生界的原始含金建造——元古界双溪坞群以及衍生含金建造——震旦-寒武系陈蔡群和前寒武系左溪混合岩。它们在岩石成因、金银含量及分布、微量元素组合及特征等方面,均具有一定的继承和演化关系。通过变质-热液、火山-热液等地质作用,含金建造为隆起带中各类金矿床的形成提供了必要的成矿物质。     

云南晋宁梅树村剖面前寒武系—寒武系界线化石Sm-Nd同位素年龄测定

本文首次采用化石Sm-Nd等时线方法测定了前寒武系—寒武系界线的年龄。样品采自云南晋宁梅树村剖面的中谊村段磷块岩。根据4个软舌螺化石样品得出的年龄值为距今562.8±7.9Ma;由这4个样品和2个胶磷矿样品获得的年龄值为562.1±5.7Ma,这些数据表明,略低于中谊村段的前寒武系-寒武系界线参考点A的年龄距今约为570Ma,而位于中谊村段近顶部的界线参考点B的年龄距今约为560Ma。该结果为准确标定寒武系底界在国际地质年表中的位置提供了重要依据。     

中国前寒武纪—寒武纪过渡期海水Sm-Nd同位素特征及其意义

对我国3个前寒武系—寒武系界线剖面(云南晋宁梅树村剖面、四川峨嵋麦地坪剖面和新疆柯坪乌什剖面)地层中小壳化石和胶磷矿样品的Sm-Nd同位素测定表明,在前寒武纪—寒武纪过渡时期,这3个相距遥远的地区的海水是共洋的,海水的ε_(Nd)(T)值为-6.6±0.5.在距今610—500Ma期间,中国海水的ε_(Nd)(T)值在-5.7到-6.6之间,变化很小。研究结果证明,当时除古太平洋和古大西洋之外,还存在一个“古亚澳洋”,而中国海水属于“古亚澳洋”的一部分。样品测定的Sm-Nd模式年龄的为1.8Ga,它反映中国海水周围陆源区的平均年龄。     

贵州织金三甲寒武系戈仲伍组含磷岩系稀土富集规律研究

对贵州织金三甲地区寒武系底部戈仲伍组含磷岩系稀土元素、微量元素和一些常量元素等在剖面上的变化规律进行系统的研究，并结合剖面上小壳动物化石富集特点，认为寒武系底部戈仲伍组中有两个磷和稀土成矿期，稀土含量与磷含量成显著的正相关关系，而与小壳动物化石丰度没有显著相关性。     

中蒙边界区新发现的特大型推覆构造及伸展变质核杂岩

本文论述了内蒙古自治区海西-印支造山带内发现一特大型推覆构造和伸展变质核杂岩,两构造的时代均为中生代,但前者较早,推覆体走向近东西,中元古界白云岩自北向南推覆在寒武至三叠系地层上,直观推覆距70km,推测断距140km以上,变质核杂岩主要由糜棱岩组成,在推覆体范围内构成一北东向穹窿背斜并构成伸展拆离断层的下盘,糜棱岩面理平缓,拉伸线理总体向南南东倾伏,剪切指向标志表明为正断式运动,造山后推覆与伸展构造的共存提出一个重要的构造动力学问题。     

煤中砷与硫洗选过程迁移和燃烧过程释放特性

以宁武煤田两个洗煤厂原煤及洗选产物为研究对象，采用微波消解与氢化物发生-原子荧光光谱相结合方法考察了洗煤过程硫和砷迁移规律，采用砷质量平衡验证的逐级化学提取法探讨了原煤、精煤、矸石、洗中煤和煤泥燃烧后硫和砷形态转化与释放特性及其依赖性。原煤中20%-28%硫和砷迁移至精煤中，46%-61%迁移至矸石中，Pearson相关系数结果表明，样品中无机矿物质是硫和砷迁移的控制因素。精煤中有机硫和砷提高至30%-50%，而矸石中无机硫和砷占比达90%以上，说明原煤及洗选产物中砷与硫赋存形态具有一定相关性。精煤中较多的有机硫和砷在500℃以下伴随水分和挥发分析出呈现明显释放特征，矸石中以无机态为主的砷则主要在500-1000℃伴随黄铁矿和硫酸盐等矿物质分解与硫一起释放，体现了原煤及洗选产物燃烧时硫与砷释放的同步性。精煤中硫和砷释放速率最快，300和200 s分别达到最大释放率80%-95%和60%-75%；矸石中最慢，300 s时砷达到最大释放率40%-45%，而硫600 s时仍未达最大释放率；洗中煤和原煤介于精煤和矸石之间，样品燃烧时硫和砷赋释放速率差异是由其固有赋存形态差异所致。     

梅树村阶及前寒武系—寒武系界线的全球生物地层对比

梅树村阶生物化石丰富、演化序列清楚。依据梅树村剖面所建立的小壳化石分带、遗迹化石序列及前寒武系一寒武系界线层型点(“B”点)(即第Ⅰ,Ⅱ化石带或6和7层的分界),具有广泛的区域和洲际对比性,不仅在碳酸盐沉积区而且也适用于碎屑岩沉积区的对比。根据梅树村阶小壳化石组合带可与苏联西伯利亚、蒙古、英国英格兰中部、澳大利亚南部及加拿大西北部进行良好对比。依据遗迹化石序列可与苏联俄罗斯地台、西北欧、英国、西班牙、澳大利亚、美国西部及加拿大东南部等地区进行广泛的洲际对比。     

钢铁在磷砷硅锰联合快速测定的改进

对钢铁中砷含的快速测定方法提出了改进意见，提高了稳定性和准确度，拟定了硅、锰、磷、砷四元素的联合快速测定新规程。     

缺氧沉积物中重金属形态连续萃取方法的稳定性研究

考察了海水养殖区域缺氧沉积物中重金属形态连续萃取法萃取过程中溶液pH值、温度变化和胶体形成对形态分离结果的影响。结果表明,连续萃取法Step1萃取酸溶态时,萃取液pH值的轻微升高使Pb和Zn的萃取结果明显降低;Step2萃取还原态时,萃取液pH值明显升高对重金属的萃取结果影响很小;Step3萃取有机质结合态时,萃取液pH值的降低对重金属萃取结果影响较小(除Pb外)。由于连续萃取法中各步萃取反应的热力学过程不同,Step1和Step2萃取后溶液温度轻微升高而在Step3中溶液温度稍微降低,溶液温度变化(<2.5℃)对重金属形态的影响很小。在Step1、Step2和Step4萃取过程中胶体的形成和存在,对萃取液Cd、Zn和Cu有明显的吸附影响;而在Step3萃取中萃取剂的分散作用有效控制了溶液中胶体的形成。因此采用连续萃取方法评价沉积物中的重金属形态时,控制萃取液pH值和胶体形成有利于提高萃取结果的稳定性和准确性。     

高效液相色谱-电感耦合等离子体质谱法同时测定果蔬中6种砷形态

建立了一种同时测定果蔬中亚砷酸根、砷酸根、砷胆碱、砷甜菜碱、一甲基砷酸和二甲基砷酸等6种砷形态的高效液相色谱-电感耦合等离子体质谱分析方法。样品经甲醇水提取,采用阴离子分析柱,50 mmol/L碳酸铵溶液和水作为流动相进行梯度洗脱,高效液相色谱分离,电感耦合等离子体质谱进行定性和定量分析。在0.5～50μg/kg范围内...     

Characterization of lead and arsenic contamination at Barber Orchard, Haywood County, NC

Barber Orchard is a residential community in Western North Carolina that was declared a U.S. EPA Superfund Site in September 2001 because of elevated levels of arsenic, lead, and organochlorine compounds in the soil. The contamination was introduced by pesticides (e.g., lead arsenate, DDT) when the land was employed as an apple orchard. Concentration levels of lead and arsenic in soil were measured throughout two plots by inductively coupled plasma optical emission spectrometry. A linear relationship was observed between the moles of lead and arsenic. Sequential extraction procedures were employed to characterize the mobility and bioavailability of the metals. The major forms of both elements were bound to iron-manganese oxides. In general, the relative composition of the metal species did not statistically vary with depth, although higher concentration levels were observed near the surface. Brake ferns (Pteris vittata) were employed in greenhouse phytoremediation experiments employing soil which had been homogenized to a uniform concentration level. Considerable variation was observed in the amount of arsenic absorbed by the ferns.     

In silico analysis of metal coordination geometry in arsenic,beryllium, and lead bound structures

Metal toxicity is a potential hazard to health and toxic effects of metals have been implicated in many diseases. Understanding the interaction of toxic metals becomes vital to prevent hazards following its association in living systems. Coordination chemistry helps in predicting the metal environments like coordinating residues, coordination space, metal coordination geometry, etc. Our work aimed at predicting the coordination of toxic metals arsenic, lead, and beryllium. In this work, we analyzed coordination for each metal from a set of arsenic, beryllium and lead bound structures which were retrieved from the Protein Data Bank. The structures were validated using B-factor and occupancy of the coordinating residues towards the metals. Coordination patterns such as chelate residues, chelate length, geometry, coordination number and structural architecture were predicted. Coordination geometry of the metals was exposed beyond the coordination space with their coordination number ranging from 2 to 11. Analysis of metal environment revealed the acidic amino acids aspartic acid, glutamic acid, and the basic amino acids lysine, histidine, and cysteine to be predominant in coordinating with the metals. Chelate patterns like DDVMITAK, DWNVTVK, ESGKNSS for beryllium, CCCSK, DSDWD for lead and FLICVI and LKHHKEE for arsenic were predicted to be common through extended coordination space. The distinct molecular geometries such as pentagonal bipyramid and square planar were observed only in lead bound structures but not in beryllium and arsenic bound structures. Beryllium had a larger influence than arsenic and lead, based on conformational changes owing to the presence of the metals. Our coordination study puts forth several propositions based on the metal environment that would help in designing chelation strategies.     

Capillary electrophoresis of inorganic anions

This review deals with the separation mechanisms applied to the separation of inorganic anions by capillary electrophoresis (CE) techniques. It covers various CE techniques that are suitable for the separation and/or determination of inorganic anions in various matrices, including capillary zone electrophoresis, micellar electrokinetic chromatography, electrochromatography and capillary isotachophoresis. Detection and sample preparation techniques used in CE separations are also reviewed. An extensive part of this review deals with applications of CE techniques in various fields (environmental, food and plant materials, biological and biomedical, technical materials and industrial processes). Attention is paid to speciations of anions of arsenic, selenium, chromium, phosphorus, sulfur and halogen elements by CE.     

Determination of lipid‐soluble arsenic species in seaweed‐eating sheep from Orkney

This work is part of an ongoing research study towards an understanding of the complete metabolism of arsenosugars in mammalian organisms when ingesting seaweed, using the North Ronaldsay (NR) sheep as a model organism. We focus on the analysis of only those arsenic species bound to the lipids of the feed (Laminaria digitata), faeces and the tissues of the NR sheep using a novel enzymatic hydrolytic method that is simple and reliable. This rare breed of sheep, found in the remote Orkney Islands in the north of Scotland, live the entire year on the beaches and eat seaweed that is washed ashore (up to 3 kg daily). Previous studies on arsenic fractionation in muscle, kidney and liver tissues revealed that most of the arsenic is concentrated in the fat fractions of these tissues (muscle fat: 61%; liver fat: 66%; kidney fat: 25%) rather than in the non‐lipid fractions. Hence, this study was undertaken in order to determine the arsenic species bound to lipids in the muscle, kidney and faeces of NR sheep and to compare these with the arsenic species bound to the lipids of the L. digitata consumed. The enzymatic hydrolytic procedure has been successfully employed for the first time to cleave the arsenic species cleanly from the rest of the lipid structure. This makes the arsenic species water soluble and enables their direct determination by high‐performance liquid chromatography coupled with inductively coupled plasma mass spectrometry. Dimethylarsinic acid (DMA(V)) and monomethylarsonic acid (MA(V)) were found to be the major hydrolysed arsenic species bound to the kidney and muscle lipids, whereas arsenosugar‐1 was found to be the major hydrolysed arsenic species in L. digitata lipids. On the other hand, DMA(V) was found to be the major arsenical obtained after the enzymatic hydrolysis of the faeces lipids. These results seem to suggest that both direct absorption and biotransformation of the absorbed organoarsenicals are the likely reasons for their occurrence and accumulation in the NR sheep tissues. Copyright © 2003 John Wiley & Sons, Ltd.     

Urinary arsenic speciation by high-performance liquid chromatography/atomic absorption spectrometry for monitoring occupational exposure to inorganic arsenic

Total urinary arsenic determinations are often used to assess occupational exposure to inorganic arsenic. Ingestion of sea food can increase the normal background levels of total arsenic in urine by up to an order of magnitude, but this arsenic has relatively little toxicity; it is tightly bound as arsenobetaine. The excretion of inorganic arsenic and its metabolites dimethylarsenic acid (DMA) and monomethylarsonic acid (MMA) is not influenced by the consumption of arsenic from sea food. Specific measurements of DMA, MMA and inorganic arsenic provide a more reliable indicator or exposure than total urinary arsenic levels. An automated atomic absorption method involving high-performance liquid chromatographic separation of the arsenic species and continuous hydride generation is described for the determination of arsenite, arsenate, DMA and MMA at μg As l^?1 levels. The method is used to study normal urinary arsenic levels in laboratory staff and arsenic excretion by exposed workers.     

Simultaneous Forecast for Three Speciations of Heavy Metal Elements Using Fuzzy Cluster-Artificial Neural Network

The three speciations(water extract, adsorption and organic speciations) of Cu, Zn, Fe and Mn in geo-chemical samples were determined by fuzzy cluster-artificial neural network(FC-ANN) method coupled with atomic absorption spectrometry. A back-propagation artificial neural network with one input node and three export nodes was constructed, which could forecaste three speciations of heavy metals simultaneously. In the learning sample set, the three speciations of each element were allowed to change in a wide concentration range and the accuracy of the analysis was apparently increased via the learning sample set optimized with the help of the fuzzy cluster analysis. The average relative errors of the three speciations of Cu, Zn, Fe or Mn from 100 geo-chemical samples were less than 5%. The relative standard deviations of the three speciations of each of four heavy metals were 0.008%―4.43%.     

煤中砷赋存状态与其脱洗率的关系

煤中砷是环境危害敏感有害微量元素之一,美国在1990年通过的清洁空气法修正案,对包含砷在内的11种微量元素表示关切。Swaine也把煤中砷列为对人类明显有害的元素之一。由于燃煤,砷曾经引起过诸多环境问题,在这些问题中尤以捷克和我国因燃用高砷煤所引发的环境问题最为突出。在捷克某使用高砷煤的发电厂下行风向的蜜蜂大量死亡,而我国则在贵州西南出现了大批的砷中毒患。     

The Fossils in Shangxi Group and Its Implication for Tectonics, Southern Anhui, China

The Shangxi Group is the local name in southern Anhui Province and it is believed to be the equivalence of the well-known Banxi Group in Hunan Province, southern China. So the area occupied by the Shangxi Group was regarded as a part of the "Jiangnan old land" of Presinian till it was challenged by the present authors years ago. After we postulated that there may be some strata of Palaeozoic Era in Shangxi Group, some microfossils and then macrofossils of Palaeozoic were found in some part of it. The macrof os-sils, Lingula sp. , Conulariid and the microfossils indicate that most units of the Shangxi Group are Palaeozoic strata. Based on the discovery of these fossils and the recognition of the tectonic-setting of the different tectono-petrologic units in the Shangxi Group, three different stratigraphic sequences (island-arc volcanics, back-arc sediments and the cover of passive margin of Yangtze Continental Plate) are established and the tectonic evolution of them is postulated in the present paper. Al