An Investigation of Digestion Methods for Trace Elements in Bauxite and Their Determination in Ten Bauxite Reference Materials Using Inductively Coupled Plasma‐Mass Spectrometry

Trace elements from samples of bauxite deposits can provide useful information relevant to the exploration of the ore‐forming process. Sample digestion is a fundamental and critical stage in the process of geochemical analysis, which enables the acquisition of accurate trace element data by ICP‐MS. However, the conventional bomb digestion method with HF/HNO₃ results in a significant loss of rare earth elements (REEs) due to the formation of insoluble AlF₃ precipitates during the digestion of bauxite samples. In this study, the digestion capability of the following methods was investigated: (a) ‘Mg‐addition’ bomb digestion, (b) NH₄HF₂ open vessel digestion and (c) NH₄F open vessel digestion. ‘Mg‐addition’ bomb digestion can effectively suppress the formation of AlF₃ and simultaneously ensure the complete decomposition of resistant minerals in bauxite samples. The addition of MgO to the bauxite samples resulted in (Mg + Ca)/Al ratios ≥ 1. However, adding a large amount of MgO leads to significant blank contamination for some transition elements (V, Cr, Ni and Zn). The NH₄HF₂ or NH₄F open vessel digestion methods can also completely digest resistant minerals in bauxite samples in a short period of time (5 hr). Unlike conventional bomb digestion with HF/HNO₃, the white precipitates and the semi‐transparent gels present in the NH₄HF₂ and NH₄F digestion methods could be efficiently dissolved by evaporation with HClO₄. Based on these three optimised digestion methods, thirty‐seven trace elements including REEs in ten bauxite reference materials (RMs) were determined by ICP‐MS. The data obtained showed excellent inter‐method reproducibility (agreement within 5% for REEs). The relative standard deviation (% RSD) for most elements was < 6%. The concentrations of trace elements in the ten bauxite RMs showed agreement with the limited certified (Li, V, Cr, Cu, Zn, Ga, Sr, Zr and Pb) and information values (Co, Ba, Ce and Hf) available. New trace element data for the ten RMs are provided, some of which for the first time.     

Production and Certification of Synthetic Selenium Isotopic Reference Materials

Due to intensive research into selenium isotopes in recent years, the increasing requirement for reliable and comparable measurement results has created a strong demand for selenium isotopic certified reference materials (iCRM) that were previously not available. To address this, eleven selenium iCRMs were developed, including ten synthetic iCRMs (GBW 04447–GBW 04456) and one natural iCRM (GBW 04457). The synthetic iCRMs were prepared with ⁷⁶Se, ⁷⁸Se, ⁸⁰Se and ⁸²Se solutions and a natural selenium solution; the natural iCRM was prepared with highly pure selenium material. The property values of isotope ratios in these iCRMs were certified by calibrated mass spectrometry with a collision cell multi‐collector ICP‐MS. The mass discrimination effect of the instrument was corrected with corresponding ⁷⁸Se/⁷⁶Se isotope mixtures and ⁸²Se/⁷⁶Se isotope mixtures, which were gravimetrically prepared with purified, isotopically enriched selenium materials. Homogeneity and stability tests were performed, and no significant influences were found. The uncertainty of the property values of the iCRMs was evaluated according to the Guide to the Expression of Uncertainty in Measurement (GUM) of ISO/BIPM and ISO Guide 35. The δ^82/76Se value of GBW 04457 relative to NIST SRM 3149 was also calculated. These iCRMs are intended for use in calibration of instruments and evaluation of methods for the determination of selenium isotope ratios.     

冻融循环对不同孔隙率页岩相似材料影响的试验研究

基于地质力学模型试验的相似理论,针对寒区岩体工程,分别制作了5种不同孔隙率的页岩相似材料,进行冻融循环试验,探究不同孔隙率的页岩相似材料在冻融前后,其主要物理力学参数的变化规律。试验研究表明：在冻融循环后,页岩相似材料的单轴抗压强度、三轴抗压强度、弹性模量、粘聚力、内摩擦角有不同程度的减小,孔隙率、泊松比有不同程度的增大。页岩相似材料的物理力学参数受冻融循环的影响随孔隙率的增大先增大后减小,孔隙率处于9.4%~13.6%时,受冻融循环影响最大;孔隙率处于5.8%~9.4%时,受冻融循环的影响随孔隙率的增大有增大的趋势;孔隙率处于13.9%~19.1%时,受冻融循环的影响随孔隙率的增大有减小的趋势。研究结果可以为西部寒区的岩土工程建设和减灾提供相关的科学依据。     

四川盆地下古生界硅质页岩层系中硅质来源及其对有机质保存的影响初探

四川盆地下古生界两套硅质页岩层系是其重要的页岩气产层,五峰组—龙马溪组硅质含量与TOC及含气量呈正相关性,暗示硅质矿物对该地区页岩气的生成具有重要意义。但硅质来源复杂,且存在后期硅质流体的注入。因此,本文在总结前人的研究成果基础上,对四川盆地寒武系底部硅质岩系与五峰组—龙马溪组硅质岩系的硅质特征进行了详细的岩石学分析,揭示了3种硅质来源特征：①同沉积无机硅质流体;②生物硅;③后期无机硅质流体。其中寒武系底部以同沉积无机硅质流体与生物硅来源为主,同沉积硅质流体导致有机质快速石化埋藏,有机质内部结构及形态保存较好;五峰组—龙马溪组硅质来源以后期无机硅质流体与生物硅来源为主,有机质在保存过程中受硅质流体的影响很小,有机质腐泥化作用充分,内部结构和形态多数保存较差。该研究初步揭示了两套页岩层系的硅质发育岩石学特征,及其对有机质保存的影响,期望能为四川盆地两套页岩气储层差异性提供新的思路与基础地质数据。     

粤港澳大湾区地下水资源特征及开发潜力

粤港澳大湾区是中国开放程度最高、经济活力最强的区域之一,在国家发展大局中具有重要的战略地位,大湾区未来的发展离不开水资源的支撑和良好的水生态环境。近年来,随着大湾区经济的快速发展,人口激增,需水量上升,水资源环境问题也日益突出,水安全保障程度不足;地下水是水资源的重要组成部分,具有水量稳定、水质较好的特点,可作为重要的应急备用水源。本文从地下水资源着手,系统梳理了大湾区水资源环境条件、地下水资源状况、特征和开发利用潜力,并提出了应急后备水源地建议,得到以下认识:(1)地下水可划分为松散岩类孔隙水、碳酸盐岩岩溶水、基岩裂隙水三大类,其中松散岩类孔隙水和基岩裂隙水分布最广;(2)湾区内地下水水化学类型较为复杂,丘陵山区以HCO_3-Na型、HCO_3-Ca型及HCO_3-Na+Ca型为主,冲积平原及山间盆地以HCO_3+Cl-Na型及HCO_3+Cl-Na+Ca型为主,三角洲地区以Cl-Na型微咸-咸水为主;(3)西江、北江及东江干流构成湾区内地下水排泄的总渠道,各支流为地下水的局部排泄基准面,地下水动态变化具季节性特征;(4)地下水整体水质较好,Ⅰ-Ⅲ类水占比高达66.25%,从丘陵山区到三角洲平原,水质呈变差趋势,尤其在广州、江门、中山、东莞等城市周边水质较差,超标因子主要为氨氮、氯化物、氟化物、硫酸盐等,三角洲地区发育大量"铁质水"和"氨氮水",水质性缺水问题突出;(5)地下水开发利用程度很低,东莞及中山等城市基本未开发利用地下水,在各类地下水中,碳酸盐岩岩溶裂隙水具有规模开采的开发利用潜力;(6)综合分析相关资料,提出将广花盆地等10处富水块段作为应急水源地备选,经初步计算每年可为大湾区提供约4.18亿m~3的应急水源保障。为应对突发性水质污染及极端干旱气候等大规模供水危机,保障粤港澳大湾区用水安全,促进大湾区高质量发展,建议加强大湾区的基础水文地质调查工作,掌握地下水的水位、水质、水量的动态变化特征,精准计算可用于应急备用开采的地下水储存量。     

水基钻井液防塌封堵材料封堵特性实验研究

提高钻井液封堵能力是有效解决硬脆性页岩、煤层等复杂地层井壁失稳的主要技术手段。本文以在一定温度、压力条件下30 min的滤失量为评价标准,对几种封堵材料的封堵特性进行了实验研究。结果表明：除超细碳酸钙外,其他材料随着加量的增加,封堵效果越来越好;乳化沥青、乳化石蜡和油溶性酚醛树脂随着温度的升高,封堵效果变差,而聚乙二醇和聚酯先变差然后又有一定程度的恢复;聚酯和超细碳酸钙能够快速封堵微裂缝;几种封堵剂均对钻井液的流变性能有较明显的影响。对各封堵材料的封堵机理分析表明：不同的封堵材料具有不同的封堵特性,分别适应不同的温度、压力条件。只有根据井下实际情况,有针对性地选择与之相适应的封堵材料,才能有效提高水基钻井液的封堵能力。     

深孔纳米复合水泥基护壁堵漏材料研究

本文围绕深部钻探技术中护壁堵漏材料性能的实际需要,研制了一种深孔纳米复合水泥基护壁堵漏新材料。首先,通过分析100 ℃条件下2种水泥材料的基本性能,确定了G级油井水泥为胶凝材料;然后,基于深孔钻探护壁堵漏材料的性能缺陷,采用特种纤维、纳米材料针对性改善水泥基浆液的力学性能,并优选早强剂（ZQ）、减水剂（GB）作为外加剂进行正交实验,进而研制出纳米复合水泥基护壁堵漏材料优化配方;最后,对其主要性能进行分析评价。结果表明该材料在深孔钻探中浆液流动性好,力学性能优异,综合性能满足深孔钻探护壁堵漏需求。     

含部分晶须的钛酸锂的制备及其性能表征

L i4T i5O12是一种循环性能好、有很好的充放电平台、理论比容量较大、不与电解液反应的新型负极材料,研究探索以偏钛酸和碳酸锂为主要原料制备含部分晶须的尖晶石型晶型L i4T i5O12的一种方法。通过此工艺在1 000℃煅烧8 h后在样品中约20%的晶须出现,晶须的直径≤0.5μm,晶须的长度约为7μm。     

Towing dynamics of a liferaft and fast rescue craft in a surface wave

The equations of motion for the coupled dynamics of a small liferaft and fast rescue craft in a surface wave are formulated in two dimensions using the methods of Kane and Levinson [1985. Dynamics: Theory and Applications. McGraw-Hill Inc., New York]. It is assumed that the motion normal to the wave surface is small and can be neglected, i.e. the bodies move along the propagating wave profile. The bodies are small so that wave diffraction and reflection are negligible. A Stokes second order wave is used and the wave forces are applied using Morison's equation for a body in accelerated flow. Wind loads are similarly modelled using drag coefficients. The equations are solved numerically using the Runge–Kutta routine “ode45” of MATLAB^®. The numerical model provides guidelines for predicting the tow loads and motions of small craft in severe sea states.     

基于GIS的宁波市海洋专题保障预报综合信息服务平台开发与应用

利用GIS地理信息系统、网络数据库等技术,设计开发一个集港口码头潮汐潮流精细化预报、海上搜救辅助决策、海上溢油及化学品漂移扩散辅助决策、海洋环境预警预报等功能于一体的宁波市海洋专题保障预报综合信息服务平台,为宁波涉海涉渔部门提供精准直观、灵活多样的各项专题海洋预报产品,更好地服务宁波市海洋经济的发展,提升地方政府海上突发事件应急能力。