Geostandards and Geoanalytical Research最新文献

This chapter (The Inductively Coupled Plasma) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

Chapter 5 (from Section 1 of the handbook dealing with fundamentals of measurement and instrument design) is a comprehensive treatment of the inductively coupled plasma – a significant cornerstone of modern geoanalytical spectrometry. The Chapter includes discussion of plasma formation and key components of the ICP source. This is followed by an examination of the challenges of sample introduction into the plasma, particularly focussed on the introduction of liquid samples. The physical structure of the plasma, its robustness and interference effects are fully examined prior to a section dealing with how the operation of plasma is optimised in practise.

This chapter (Laser-Induced Breakdown Spectroscopy (LIBS)) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

Chapter 13 (from Section 3 of the handbook dealing with microbeam techniques) provides first a history of the development of laser-induced breakdown spectroscopy, and of the LIBS process, followed by an examination of the fundamental principles of LIBS and its instrumentation. Discussion is then provided on the preparation of sample material, LIBS matrix effects and signal processing. Different modes of compositional analysis that can be tackled by LIBS are described, including quantitative measurement (covering isotope measurements), compositional mapping, depth profiling and the determination of physical properties of geological materials. The recent tandem coupling of LIBS with laser ablation ICP-MS instrumentation is explored. Finally, a suite of examples of LIBS analyses of silicate rocks and minerals is provided, demonstrating the utility of this measurement principle in rapid compositional assessment, detailed petrological studies and microgeochemical mapping.

This chapter (Sampling as Part of the Measurement Process) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

Chapter 1 (Part 2) forms part of Section 1 of the handbook dealing with fundamentals of measurement and instrument design. The geochemical measurement process is considered to begin when the primary sample is taken from the sampling target, rather than when that sample arrives at the laboratory. This integration of sampling within the measurement procedure enables both sampling and chemical analysis to be optimised in order to achieve a measurement procedure that is fit for its intended geochemical purpose. The key metric in judging this fitness for purpose, and hence validating a measurement procedure, is the uncertainty of each measurement value. This measurement uncertainty is explained, together with methods to estimate and express it in a way that includes the contribution from sampling, with a worked example. The resultant more realistic estimates of measurement uncertainty are shown to improve the reliability of the geochemical interpretation of measurement values.

We report the δ^142/140Ce values for thirty-three widely available geological reference materials (RMs), including igneous rocks, metamorphic rocks, sediments and soils. The Ce isotope ratios of twenty-two Chinese RMs are reported for the first time. After chemical purification using TODGA resin (50–100 μm, Eichrom, USA), Ce isotope measurements of these RMs were conducted by multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) with a combined standard-sample bracketing (SSB) and Sm-doping technique. The data quality of the Ce isotope results was assessed by repeated measurement of pure Ce reference solutions (NIST SRM 3110, JMC304, CDUT-Ce) and well-characterised geological RMs (BHVO-2, BCR-2, Nod-A-1, Nod-P-1, etc.). Our results are in excellent agreement with previously reported values within intermediate measurement precision (±0.04‰, 2s). The igneous rock and soil RMs showed limited variations in δ^142/140Ce values, which ranged from -0.036 ± 0.018‰ to 0.062 ± 0.046‰ and -0.015 ± 0.015‰ to 0.029 ± 0.009‰, respectively. The river/marine sediments and Mn nodules displayed variable Ce isotope ratios ranging from -0.005 ± 0.018‰ to 0.141 ± 0.023‰, suggesting detectable Ce isotopic fractionation during low-temperature processes.

The use of reference materials (RMs) and certified reference materials (CRMs) is essential to guarantee the reliability of measurement procedures - a major factor motivating the efforts of the geoanalytical community. This work quantifies trends and patterns in the scientific literature concerning RMs and CRMs in geochemistry for specific timespans, with the aim of evaluating historical developments, research fields, geographic shifts of research centres, and current trends. The Scopus database was surveyed for peer-reviewed full-texts (14,201 documents), which were subsequently exploited for statistical description, bibliometric mapping and cluster analysis. Mineral exploration and trace element geochemistry stimulated early research, whereas environmental subjects have grown in importance mainly since the year 2000. International standardisation was coincident with an increase of publications covering CRMs and geochemistry, and is thought to reflect the impact of ISO guidelines in this scientific activity. Other factors include investments in research facilities, creation of specialised geoanalytical journals and organisation of international meetings. The analysis shows that RMs are typically used for petrogenetic research topics, whereas CRMs are equally important for environmental sciences, chemistry and geosciences. Environmental sciences are mostly concerned with anthropogenic contamination of ecosystems by heavy metals, whereas geological interest is mainly driven by isotope geochemistry. Scientific frontiers in geoanalytical research comprise microanalytical methodologies, unconventional isotopes, rare earth elements and environmental monitoring. New trends in CRM applications also include biogeochemistry and radionuclides.

This chapter (Principles and Practice of X-Ray Fluorescence Spectrometry – 1: Fundamentals of XRF and Matrix Corrections) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of the Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

Chapter 6, Part 1 (from Section 2 of the handbook dealing with techniques for the determination of major and trace elements) considers the fundamentals of XRF spectrometry and matrix corrections in detail. Part 2 deals with wavelength dispersive and energy dispersive instrumentation. Following an introduction dealing with the analytical characteristics of XRF spectrometry, Part 1 continues with a detailed consideration of the origin and excitation of X-ray spectra. Sub-chapters that tackle the interaction of X-rays with matter and the matrix effect in geological materials follow this. Part 1 is concluded with a mathematical treatment of the correction of absorption-enhancement effects.

This chapter (Geoanalytical Metrology) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of Handbook of Silicate Rock Analysis, which was written by Philip J. Potts and published in 1987 by Blackie and Son (Glasgow). This second edition comprises chapters, written by prominent research scientists, designed to provide comprehensive overviews of the relevant techniques for the elemental characterisation of rocks and minerals. Chapters are designed to allow new practitioners to the field (including research students) to attain a comprehensive understanding of the theory, practice and capabilities of each technique, as well as being of benefit to established research geoanalysts. In addition to the content, chapter titles have been revised where appropriate to reflect progress in this field.

Chapter 1, Part 1 (from Section 1 of the handbook dealing with fundamentals of measurement and instrument design) first sets out the overarching conventions that operate in analytical chemistry, including a description of the international organisations and systems that regulate the standards governing the discipline. This is followed by coverage of the statistical basis on which geoanalytical data sets are treated, analysed and interpreted, which summarises most of the relevant tests and terminology employed in this field. The methods by which the calibration of measured signals from instrumental techniques is tackled, followed by method validation, which covers aspects including measurement uncertainty, bias, precision and trueness. Sections detailing metrological traceability and quality management conclude this chapter.

This chapter (Quadrupole Inductively Coupled Plasma-Mass Spectrometry) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of Handbook of the Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

Chapter 7 (from Section 2 of the handbook dealing with techniques for the determination of major and trace elements) describes both the history of ICP-MS, including development of the plasma sampling interface and the operation of modern ICP-MS instrumentation. Given their central importance to ICP-MS operation, ion extraction through the sampling interface, ion transmission, ion separation (with a particular focus on the quadrupole mass filter) and counting are given particular attention. Discussion of the analytical characteristics of ICP-MS particularly focusses on spectroscopic interferences (and their mitigation). Finally, an overview of geochemical analysis by ICP-MS considers drift correction, calibration strategies, and laser ablation microsampling.

Nanomaterials (NMs) have unique properties and control processes relevant to the fate of contaminants in soils, air, and aquatic systems and within the carbon cycle. Many NMs often occur in association with larger mineral grains, organic matter, or living organisms such as microbes, plants and fungi. The preservation of the spatial, textural, chemical, and mineralogical relations between NMs and minerals, organic matter, and organism (NM-associations) is of fundamental importance as it provides information about the origin and formation mechanisms of NMs. Here we review analytical approaches and techniques to study NM-associations at the bulk-, micro-, nano- and atomic-scale. We will focus on (a) X-ray diffraction and mass-spectroscopy techniques; (2) automatisms within software packages that permit the search of features without operators; (3) preparation and analytical techniques such as the focused-ion beam technology, transmission electron microscopy and atom probe tomography; (4) nano-spectroscopic techniques such as tip-enhanced Raman spectroscopy, synchrotron infrared nanospectroscopy, and nano-X-ray fluorescence spectroscopy; (5) ptychographic X-ray computer tomography. This review paper concludes with selected new perspectives such as (a) the characterisation of NM-precursors, (b) the role of NM-associations in the stabilisation of soil organic matter and (c) the interaction of NM-associations in wildfire smoke with contaminants from other sources.