直接熔融热电离质谱法测定硼酸盐矿物中的硼同位素组成

为简化一些硼同位素样品的前处理过程,本文用直接熔融法,即待测样品直接在电离带上进行熔融后测定其硼同位素值。本文测定了柱硼镁石、电气石、钠硼解石、碳化硼、硼化硅等几种含硼化合物中的硼同位素组成,并与传统的溶样方法进行了比较。结果表明,直接熔融法可以快速且高精度测定上述几种化合物中硼同位素组成,相对内精度小于0.05‰,为此类含硼化合物的硼同位素测定提供了一种新的测试方法。     

锑的地球化学行为以及锑同位素研究进展

火山和成矿地质现象表明硼可以在含水流体和气体中运移,本文应用离子选择电极法测定水热气体中硼的溶解度,以揭示硼的气态迁移能力。使用氟硼酸盐选择电极,测定了经氟硼酸化的硼酸标准溶液和含硼气体凝结水的电位,当硼含量处于地质流体的主要范围内（0.52～524.50 mg/L）时,电极电位与硼浓度的对数呈现出灵敏度很高的能斯特线性关系,标准曲线具有很好的稳定性和重现性。本方法测定硼的检出限为0.13 mg/L,低于饮用水标准规定的硼含量限值,适用于测定水热气体中的硼含量。硼酸挥发实验显示,硼在150℃、0.37 MPa水蒸气中的含量可达0.65%～0.72%,与富硼火山喷气的硼含量相符,显示硼在高温水热条件下可在气相中显著迁移,且H₃BO₃气态分子是硼的主要迁移形式之一。矿床地质特征和实验表明,硼的气态迁移和电气石化与稀有金属型伟晶岩的形成和矿化以及某些热液-气成型Sn-W、Mo矿床和斑岩型Cu、Au矿床的形成密切相关。     

电气石中硼的溶出机制初探

电气石是一种以含硼为特征的硅酸盐矿物,矿物中硼含量在2.78%~3.4%之间,但电气石中的硼被束缚在稳定的晶体结构中难以溶出而被植物吸收,从而影响电气石中硼在农业上的应用。本文通过一系列实验与检测分析,对电气石中硼的溶出机制进行了研究,发现＂高温煅烧十活化剂＂相结合的方法能有效地将电气石中硼的溶出,并初步选定Na2CO3为理想的活化剂,为开发电气石硼肥奠定了理论基础。     

鲜水河断裂带富硼地热水中稀土元素分布特征及其对硼来源的指示意义

高温地热系统地热水中普遍富含高浓度的硼,其来源的研究一直是地热地质学者关注的热点问题。尽管众多的学者对地热水中硼形成机理开展了广泛的研究,但富硼地热水中稀土元素的分布特征及其迁移规律能否指示热水中硼的来源尚不清楚。本研究以鲜水河断裂带富硼地热水为研究对象,通过野外调查取样、室内测试分析、水文地球化学模拟和综合研究等技术手段和方法,探究断裂带地热水中硼和稀土元素的分布特征和迁移规律。研究结果显示：鲜水河断裂带地热水中硼含量90%超过我国饮用水标准规定值0.5 mg/L（地热水中硼含量最大值为10.50 mg/L）;地热水中稀土元素含量为0.08～3.49 μg/L,且主要以LnCO₃⁺和Ln(CO₃)₂⁻的络合物形态存在。地热水稀土元素PAAS归一化模式表现为重稀土元素相对于轻稀土元素富集（(Nd/Yb)_SN均值为0.41）,且具有较显著的Eu（均值为0.34）和Ce（均值为0.07）正异常特征。地热水中硼和稀土元素的迁移均受到赋热含水层长英质和碳酸盐岩类矿物溶解过程的影响,且地热水中稀土元素的地球化学特征一定程度上可以指示地热水中硼的富集过程。研究成果拓展了稀土元素在富硼地热水研究中的应用,能为揭示富硼地热水成因研究提供依据。

     

微波消解-电感耦合等离子体质谱法测定煤中的硼

煤中硼的准确测定对于研究成煤的沉积环境具有重要意义。微波消解-电感耦合等离子体质谱(ICP-MS)可以有效地测定煤中的大部分微量元素,但由于硼易挥发等特殊的物理化学性质,致使硼的测定过程较为繁琐,测试结果不够准确。本文对微波消解ICP-MS测定煤中硼含量的分析方法进行了改进。样品中加入磷酸、硝酸和氢氟酸,用微波消解仪消解完全,置于电热板加热赶酸完毕后用硝酸提取。硼的卤化物易挥发,磷酸的加入使硼与磷酸结合生成难挥发的稳定络合物,起到了固硼的作用。ICP-MS测定中采用铍作为内标,通过在线加入的方式有效地补偿了基体效应产生的影响;用稀氨水冲洗进样系统,很好地降低了硼的记忆效应;选择高分辨率模式来测定,避免了12C和40Ar4+等质谱峰的干扰。方法的仪器检出限(0.22ng/mL)和方法检出限(0.34 ng/mL)较低,方法精密度(RSD)小于0.6%,灵敏度高,且测定标准样品的准确度良好。该方法简单快速,适用于批量分析煤样中硼的含量。     

微波消解-电感耦合等离子体发射光谱法分析食品中的总硼

采用微波消解-电感耦合等离子体原子发射光谱法(ICP-OES)测定了不同食品中总硼的含量。对微波消解样品前处理条件和仪器参数进行了选择和优化。方法对硼元素的检出限为0.10 mg/kg。方法的精密度(RSD,n=6)为1.6%~6.8%;回收率为96.5%~104.0%。方法用于分析国家一级标准参考物质GBW 07605(茶叶)、GBW 08501(桃叶)、面粉与鱿鱼粉中的硼,测定值与标准值或参考值吻合。     

中国煤中的锗和镓

煤中的锗和镓是可利用伴生元素。我国多数煤中锗的含量处于0.5～10mg/kg之间,平均4mg/kg;煤中镓的含量处于1～20mg/kg之间,平均9mg/kg。我国云南临沧盆地发现有特大型锗矿床,锗赋存在第三纪褐煤中,含量达3000mg/kg以上,呈有机质吸附态和粘土矿物吸附态为主要赋存方式。     

中国硼资源及硼泥资源化综合利用前景

硼是用途广泛的重要非金属元素,中国已探明硼资源总储量为4 908万t,其中90%以上集中分布于辽宁、吉林、青海和西藏4个省区,矿床类型以沉积变质型和现代盐湖沉积型为主。几十年来,硼资源被过度无序开采,使得以硼镁矿为代表的易开采型硼富矿现已濒临枯竭,由此,加强对硼铁矿、现代盐湖和地下卤水型硼资源的进一步开发利用十分必要。目前,硼资源主要是通过制成硼砂和硼酸加以利用,在采用碳碱法制备硼砂和采用硫酸一步分解法、硼砂二步法制备硼酸的过程中,会产生大量的硼泥废弃物,这些废弃物易造成严重的环境污染,制约硼工业的发展。如果硼泥能够得到充分利用,既能解决硼资源的进一步开发利用的难题,也能缓解环境压力。因此,提出了硼泥在建材、环境材料、冶金及有价成分回收等领域资源化利用的绿色途径,并以提高硼的利用价值和降低环境污染为目的,对硼资源合理开发、硼泥综合利用和高新含硼材料发展进行了展望。     

塞尔维亚贾达尔盆地超大型锂硼矿床

锂和硼有着广泛的用途,我国常年大量进口锂和硼矿石。近些年在塞尔维亚贾达尔盆地中发现一个特殊的超大型锂硼矿床,与Rio Tinto、Pan Global Resources和Ultra Lithium等公司一样,我国地勘单位正在这一矿区进行勘查工作,因此对该地区的锂硼矿床地质特征进行总结和报道很有必要。该矿床的矿石矿物是世界独有的既含锂也含硼的羟硼硅钠锂石(Jadarite)[LiNaSiB_3O_7(OH)],其含B_2O_3 47.2%,含Li_2O 7.3%,密度2.46g/cm~3。已有资料显示,找矿标志层为中新统湖相沉积岩中的凝灰岩层,矿体具有电阻率小于4.4Ω·m和重力异常值小于-15mGal的特征。该矿床设施齐全,且选矿和化工处理简便,短期内可获得硼和锂产品。     

云南省临沧市勐托新近系褐煤的微量元素地球化学特征

为研究云南临沧勐托新近系褐煤的微量元素地球化学特征,共采集了11个褐煤样品,采用ICP MS和ICP CCT MS(As和Se)对煤中微量元素进行了测试。结果表明：与中国煤相比,勐托褐煤中Rb(96.1 mg/kg)、Sb(15.3 mg/kg)和Cs(25.9 mg/kg)显著富集,W(10.6 mg/kg)和U(20.2 mg/kg)富集,Be(7.84 mg/kg)、Ga(16.1 mg/kg)、As(11.6 mg/kg)、Cd(0.67 mg/kg)、Sn(6.66 mg/kg)、Pb(34.6 mg/kg)、Bi(3.86 mg/kg)和Th(28.2 mg/kg)稍富集,微量元素组成与大寨富锗煤不同,与酸性花岗岩物源供应有关。勐托褐煤中REY含量范围为121~420 mg/kg,平均251 mg/kg,均较大寨富锗褐煤高,且以Ce显著正异常和Eu显著负异常为特征,明显区别于大寨褐煤,Eu负异常和上陆壳标准化的REY分配模式均表明勐托褐煤中稀土元素受盆地周边花岗岩风化陆源碎屑供应影响。     

中国煤中的铀、钍和放射性核素

中国煤中的铀平均含量为3mg/kg,在某地富铀煤中检测到的最高值达25660mg/kg,其赋存状态主要是与有机质相结合的方式;钍平均含量6 mg/kg,没有发现异常现象.南方一些地区的石煤中含有较多的放射性核素,并且容易在灰渣中富集,综合利用时应加强监控,以避免产生危害.     

Effect of pH on boron coprecipitation by calcite: further evidence for nonequilibrium partitioning of trace elements

The influence of pH and concentration on boron coprecipitation by calcite were evaluated under near-equilibrium conditions at 25°C. Calcite was precipitated by adding a metastable polymorph (vaterite or aragonite) to a solution of known boron concentration. This method maintains a nearly constant solution composition during the slow conversion of the metastable polymorph to calcite.Boron uptake in calcite was found to be strongly pH-dependent, increasing two orders of magnitude from pH 8.5 to pH 10.5. Boron incorporation into calcites precipitated from vaterite-saturated solutions was five times greater than in calcites precipitated from aragonite-saturated solutions. Ostensibly, these results suggest that the calcite precipitation rates were not low enough to attain equilibrium partitioning of boron into calcite. However, scanning electron micrograph analyses showed that the prevalent crystal forms of calcite generated from aragonite and those generated from vaterite were distinctly different. The different quantities of boron incorporated into these calcites may reflect different crystal growth mechanisms, consistent with face-dependent, nonequilibrium partitioning of trace elements in calcite.At a constant pH of 9.0, boron uptake increased from less than 15 to over 290 mg/kg CaCO₃ as the solution boron concentration was increased from 5 to 100 mg/kg. Our results agree with those of other investigators, despite differences in solution composition, and calcite precipitation techniques used. The agreement between the studies may be because the crystal growth morphology of the calcite was rhombohedral in both cases.     

中国煤中的氟

氟是煤中所含微量元素中丰度较高的少数几种元素之一。对我国581个煤样分析数据的统计表明,多数样品氟含量处于20～300mg/kg,平均40mg/kg,个别超过1000mg/kg。氟在煤中赋存状态有:①独立的氟矿物;②以类质同象存在于矿物晶格内;③被矿物吸附;④以F-离子形式溶于水中。在煤中所含微量元素中,氟是对植物、动物和人体健康的影响面最大的元素。     

Geoecology of ecosystem recovery at an inactive coal mine site,New Zealand

Ecological restoration of the Wangaloa coal mine in southern New Zealand is hindered by a range of geoecological factors. The site has some substrate acidification (down to pH 1) and acid rock drainage with discharge waters initially down to pH 4, although this has since risen to ca. pH 6. Surface and ground waters develop elevated sulfate (up to 700 mg/kg) during oxidation of pyrite in coal and quartz in waste rock. Coal has elevated boron content (up to 450 mg/kg) and surface waters on coal-rich waste rock have up to 6 mg/L dissolved boron. Evaporation causes formation of salt encrustations dominated by gypsum with minor boron salts. Boron is bioavailable and may be at toxic levels (>200 mg/kg) in some plants. Quartz-rich waste rock is readily eroded, and develops a cm-scale low-nutrient quartz pebble armouring layer with low water retention properties. All waste rocks including loess siltstone have low nutrient contents, and low moisture retention properties, that are barely sufficient for plant establishment. Native plants introduced to the site during rehabilitation have grown on loess substrate (up to fivefold increase in height over 3 years), with poor or no growth on coal-rich and quartz-rich substrates. In contrast, natural colonisation of manuka (Leptospermum scoparium) has been most effective at revegetation on even the most hostile substrates. This natural revegetation has been facilitated by islands of manuka established accidentally during 60 years of mining history. Manuka from local genetic stock is most viable for this revegetation, and introduced manuka seedlings have had a 70% mortality rate. Natural plant colonisation is the key step in overall ecosystem recovery, and invertebrates rapidly colonise beneath new shrubs irrespective of the nature of the substrate from vegetation islands that have high invertebrate numbers and species richness.     

Boron Determination in Twenty One Silicate Rock Reference Materials by Isotope Dilution ICP-MS

The concentration of boron was determined in twenty one geochemical reference materials (silicate rocks) by isotope dilution inductively coupled plasma-mass spectrometry. Boron was extracted from the rocks using HF digestion, suppressing boron volatilisation through boron-mannitol complexation. Sample solutions, in a diluted HCl matrix, were analysed by ICP-MS without any separation of boron from the matrix elements. The results obtained were in agreement with the literature data and indicate that using the described procedure, trace amounts of boron can be very easily determined in complex matrices with rapidity and precision. With the instrumentation and reagents used in this study, this procedure can be used for the determination of 0.5 μg g⁻¹ boron in a 15 0 mg silicate rock sample. Replicate analyses of the twenty one geochemical reference materials (GRM), ranging in boron concentration from 1.35 to 15 7 μg g⁻¹, yielded precisions (relative standard deviation) varying between 0.9 and 9.8%.     

中国煤中的氯

在煤中诸多微量元素中,氯的含量是比较高的一种元素。全国280个样品分析数据的统计,多数煤中含氯量处于50～500mg/kg,平均约220mg/kg。氯在煤中的赋存状态主要为:氯离子溶于孔隙水中;呈类质同象赋存于其他多种矿物中;独立矿物。煤中氯的较高含量给煤的利用带来的问题近年来引起人们的重视。     

Geological sources of boron and fluoride anomalies in Silurian–Ordovician aquifer system,Estonia

The objective of this study was to examine the possible natural sources of fluorides and boron in Silurian–Ordovician (S–O) aquifer system, as the anomaly of these elements has been distinguished in groundwater of western Estonia. Water–rock interactions, such as dissolution and leaching of the host rock, are considered to be the main source of high fluoride and boron concentrations in groundwater. Altogether 91 rock samples were analysed to determine if high F⁻ and B levels in groundwater could be attributed to certain aquifer forming rock types. Fluorine and boron contents in limestones and dolomites vary from 100 to 500 mg/kg and 5 to 20 mg/kg, reaching up to 1,000 and 150 mg/kg in marlstones, respectively. K-bentonites, altered volcanic ash beds, are rich in fluorine (400–4,500 mg/kg) and boron (50–1,000 mg/kg). Thus, clay-rich sediments, providing ion-exchange and adsorption sites for F⁻ and B, are the probable sources of both elements in S–O aquifer system in western Estonia.     

硼及其同位素对水体污染物的示踪研究

硼的易溶性和硼化合物的广泛使用 ,以及污水处理过程中除硼的困难 ,最终导致地表地下水体富集硼及有关污染物。海滨地下水受到海水入侵 ,硼含量及 ρ(B) / ρ(Cl)比值发生明显变化。混合、吸附、水岩等作用使得硼同位素发生分馏 ,显著区别于区域背景值。因此 ,结合其它同位素、水化学等信息 ,硼及其同位素作为良好示踪剂为研究水圈中物质的地球化学循环过程提供了新的手段。文中总结了部分天然水体的硼含量和硼同位素组成特征 ,综述了近年来用硼同位素示踪水体的污染物来源、程度和范围等方面新的研究成果。     

电气石硼肥制作技术的试验研究

硼元素是农作物生长所需的七种微量元素之一。目前给土壤补充硼元素的主要方式是施硼肥(来自硼砂矿),随着硼砂矿资源的日益减少,寻找硼替代资源日渐紧迫。笔者认为,电气石是可替代硼砂的主要矿物之一。利用电气石中硼的关键是将电气石中的硼变为可溶性硼。实验表明,高温焙烧法对电气石中硼的溶出非常有限,而用添加HF等助剂的化学法将电气石中的硼活化溶出的方法,效果较好。因此,可通过化学法先将电气石中的硼元素溶出,然后再加入部分电气石及辅料来制作电气石硼肥。