风化作用对铁陨石矿物学特征影响的探讨

本文对南丹IIICD铁陨石的矿物学特征进行了研究,并与同为铁陨石但化学分类不同的阿根廷IAB铁陨石和西伯利亚IIB铁陨石进行了对比,重点探讨了风化作用对铁陨石矿物学特征的影响.首先用偏光显微镜、静水称重、扫描电镜观察了样品的基本矿物学特征和微形貌特征,然后用振动式样品磁强计、X射线衍射与电子探针能谱半定量测试研究了样品的磁学性质、物相和化学组成.研究结果表明,南丹铁陨石在较强的自然风化作用下,光泽变弱为土状光泽,相对密度降低;风化产生的反铁磁性物质会使陨石的磁性下降;另外,样品表面物相组成也发生较大变化,以针铁矿(FeOOH)和磁铁矿(Fe₃O₄)等铁的次生矿物为主;但风化壳以下的矿物物相及化学成分均未发生明显变化,以Fe、Ni为主的铁纹石、镍纹石物相存在.     

电感耦合等离子体质谱法测定地质样品中稀散元素铬镓铟碲铊

采用电感耦合等离子体质谱技术,研究了地质样品中稀散元素铬、镓、铟、碲、铊含量的质谱分析方法。研究确定了最佳测定酸度、干扰元素的校正方法,结果令人满意。方法检出限为0.001 3~0.063μg/g,精密度(RSD,n=11)为2.00%~4.87%,优于其他方法,具有较好的灵敏度。方法快速、简便,结果准确,可用于地质样品中稀散元素铬、镓、铟、碲、铊含量的分析,适用于批量样品的快速测定。     

黄河冲积扇平原浅层地下水中氮循环对砷迁移富集的影响

黄河冲积扇平原浅层地下水砷含量超标情况严重,豫北平原的主体是黄河冲洪积扇平原。全面了解豫北平原浅层地下水氮循环驱动下砷的富集模式,对地下水资源的可持续利用和居民健康至关重要。本文采集豫北平原513组浅层地下水样品,采用原子荧光光谱法测定砷含量,原子吸收光谱和离子色谱等方法进行全分析及微量元素分析,对该地区高砷地下水的水化学成分以及地下水中硝酸盐、氨氮与砷之间的相关关系进行探究,并研究了氮循环对地下水中砷迁移富集的影响。结果表明：研究区浅层地下水中砷浓度超标率为17.3%。不同沉积环境条件下氮的赋存形态和转化方式是砷富集的重要驱动因素。山前冲洪积扇裙带中经硝化作用产生大量NO3-,浓度平均值为9.3mg/L,为各区最高,同时砷浓度为各区最低,平均值为1.3μg/L,NO3-与砷浓度之间良好的负相关性表明硝化作用产生大量NO3-,不利于含砷氧化铁的溶解;NH4+含量较高的冲洪积扇前洼地及黄河决口扇地区,为高砷地下水的聚集地,两地地下水砷浓度平均值分别为49.7μg/L和18.9μg/L,超标率达到87.5%和71.4%。地下水中砷含量与NH4+之间良好的正相关关系表明,反硝化和硝酸异化还原成铵（DNRA）过程消耗了地下水中的NO3-,生成大量NH4+,促进吸附了砷的铁氧化物的还原溶解而导致砷释放到地下水中,形成了富集砷的环境。     

Comparison of Positron Emission Tomography and X-ray radiography for studies of physical processes in sandstone

The migration of moisture in cores of porous homogeneous sandstone of Ledian age (Belgian Eocene, Tertiary) is monitored with PET (Positron Emission Tomography) and micro-focus X-ray radiography. In the case of PET, a nuclear medical imaging technique, ⁵⁵Co-EDTA (Ethylenediamine Tetraacetic acid) and R-¹⁸F were used as water-soluble tracers. The X-ray projection method has evolved from the better-known medical technique and allows a fast and accurate determination of the two-dimensional transient moisture content profiles. Results indicate that both techniques can deliver important information concerning physical processes in situ.     

高Rb/Sr岩石样品中Sr同位素多接收等离子体质谱分析校正方法研究

在利用多接收电感耦合等离子体质谱(MC-ICPMS)进行Sr同位素研究中,⁸⁷Rb对于⁸⁷Sr干扰严重。岩石样品经化学分离后,若Rb/Sr≤0.0005,可以采用传统的Rb干扰扣除方法对⁸⁷Sr/⁸⁶Sr测定值进行准确校正;但如果样品经化学分离后仍含有较高的Rb/Sr比,同量异位素的干扰不能完全消除,则无法准确校正⁸⁷Sr/⁸⁶Sr测定值,直接影响测试结果的准确度。本文针对Rb含量较高的地质样品设计两组实验,确定了⁸⁷Sr/⁸⁶Sr同位素比值与Rb/Sr元素含量比值的关系曲线,并在理论分析的基础上,提出包含同位素分馏校正在内的重叠干扰校正方法。通过实际地质样品验证,该校正方法在较高含量Rb元素共存(Rb/Sr<0.2)的Sr纯化液中,能够较为准确地测量⁸⁷Sr/⁸⁶Sr同位素比值,降低了MC-ICPMS分析地质样品中Sr同位素时对化学分离步骤的要求。而对于Rb/Sr>0.2的地质样品,因仪器分馏效应和记忆效应影响,测试精确度大大降低,无论采用何种校正方法均无法得到准确的Sr同位素组成。     

X射线荧光光谱法分析不同类型岩石中10种主量元素的测试能力验证

以28个不同类型岩石标样作外标,用玻璃熔片法制样,采用经验系数法进行基体校正,建立了X射线荧光光谱法(XRF)测定不同类型岩石中硅铝钙镁等10种主量元素的分析方法。该方法被用于参与GeoPT分析测试能力验证,15年来分析了23个不同类型的岩石验证样品。经验证该方法对SiO_2、Al_2O_3、K_2O和CaO具有非常好的分析效果(所有测定结果的|Z|2);对于MgO、MnO、TiO_2和Na_2O四个元素,尽管各有一个样品的分析结果的|Z|2,这主要是样品与标样的基体差异较大造成了低含量样品测定结果超差,但依然可获得好的分析效果;当TFe_2O_31.0%,P_2O_5含量在0.08%~0.80%区间时,分析结果的|Z|2,满足分析期望。总体上所建立的XRF分析方法稳定,可满足应用地球化学实验室测试不同类型岩石中10种主量元素的分析期望。     

Quantification of mineral matter in the Argonne Premium Coals using interactive Rietveld-based X-ray diffraction

The mineral matter in the eight reference North American coal samples of the Argonne Premium Coal series has been investigated on a quantitative basis using X-ray diffraction (XRD) techniques. X-ray diffraction data obtained from electronic low-temperature (oxygen–plasma) ash (LTA) residues, from ashes produced by heating the coals in air at 370°C, and also from the raw coals themselves, were evaluated using an interactive data processing system ( ™) based on Rietveld interpretation methods. The results from the three types of material (LTA, 370°C ash and raw coal) were compared for each sample. This allowed the components present in the raw coals in crystalline form to be recognised separately from mineral artifacts produced, particularly in the low-rank coals, from interaction of organically associated elements (Ca, S, etc.) during the two ashing processes.After the allowance for the production of any artifacts, the quantitative mineral assemblages identified from XRD of the raw coals were found to be consistent, even for coals having a relatively low ash percentage (around 5%), with the results obtained from the respective mineral concentrates prepared by the ashing methods. The effects of heating the coal to 370°C could also be distinguished, relative to the raw coal or the LTA, through changes in components such as pyrite and the clay minerals.Although some areas of uncertainty exist, particularly with magnesium in the low-rank coals, the calculated chemical compositions of the coal ash derived from the mineral mixtures identified for each coal were also found to be consistent with the results of direct chemical analysis of the respective coal ash materials.     

基于傅里叶变换质谱的烃源岩成熟度评价方法及地质意义

<正>伴随非常规油气资源的勘探开发,油气资源开采的广度和深度进一步扩大,一定程度上缓解了我国油气供需矛盾、保障了我国能源安全,同时有力推动了能源结构战略转型。但同时也对能源地质研究工作提出了新的挑战。有机质成熟度是油气评价的重要参数之一,不同成熟阶段的有机质会对应产出不同成因、不同性质、不同质量的油气,如何准确评价沉积有机质成熟度是当前油气资源勘探开发工作的关键问题之一。前人在科研实践工作中从光学、化学、谱学等角度提出了适用条件各异的成熟度评价方法,在部分地质环境中获得了良好的应用效果,但已有的成熟度指标多受测定方法原理的制约导致其适用性不同程度受限(肖贤明等,2020),制约了油气资源的高质量勘探开发。     

Crystallographic and NMR studies on sterols from green alga Chaetomorpha basiretorsa Setchell

Chemical investigation of the ethanol extract of the marine green alga Chaetomorpha basiretorsa Setchell led to the isolation of a new sterol stigmast-4,28-dien-3α,6β-diol 1 in addition to the five known sterols of β-lawsaritol 2, saringosterol 3, 24-hydroperoxy-24-vinyl - cholesterol 4, β-stigmasterol 5, 29-hydroxystigmasta-5, 24 （28） -dien-3β-ol 6. Compounds were isolated by normal phase silica gel and Sephadex LH - 20 gel colum chromatography, reverse phase HPLC and recrystalization. Their structures were elucidated by spectroscopic methods including MS, IR 1D/2D NMR and X-ray analysis. Cytotoxicity of compounds was screened by using the standard MTF method. All these compounds were isolated from the green alga Chaetomorpha basiretorsa Setchell for the first time and they were inactive （50% inhibitory concentration was greater than 10 μg/cm^3） against KB, Bel -7402, PC - 3M, Ketr 3 and MCF-7 cell lines.     

超临界萃取／气相色谱—质谱测定油页岩中的生物标志物

采用超临界萃取 /气相色谱 -质谱技术测定了广东茂名油页岩中环己烷的链取代烃、甾烷、甾烯和藿烷等生物标志物 ,其分析结果与经典索式抽提和文献结果基本相符。该方法与索式抽提法相比简单、快速、无污染和危险 ,可用于油页岩等固体样品中生物标志物的分析