Trace-element migration during crystal-plastic deformation in UHP rutile: dislocations in low-angle boundaries as high-diffusivity pathways.

2021 ◽  
Author(s):  
Rick Verberne ◽  
Hugo van Schrojenstein Lantman ◽  
Steven Reddy ◽  
Matteo Alvaro ◽  
David Wallis ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Trace Elements ◽  
Trace Element ◽  
Atom Probe ◽  
Western Alps ◽  
Trace Element Composition ◽  
Ultrahigh Pressure ◽  
Fast Diffusion ◽  
Wide Range ◽  
Element Migration

<p>The trace-element composition of rutile is commonly used to constrain <em>P-T-t</em> conditions for a wide range of metamorphic systems. Recent studies have highlighted the importance of micro- and nanostructures in the redistribution of trace elements in rutile via high-diffusivity pathways and dislocation-impurity associations. In this contribution, we investigate the effect of crystal-plastic deformation of rutile on its composition by combining microstructural and petrological analyses with atom probe tomography. The studied sample is from an omphacite vein of the ultrahigh-pressure metamorphic Lago di Cignana unit, Western Alps, Italy. Zr-in-rutile thermometry and inclusions of quartz in rutile and of coesite in omphacite constrain rutile deformation to around the prograde HP-UHP boundary at 500–550 °C. Crystal-plastic deformation of a large rutile grain resulted in low-angle boundaries that generate a total misorientation of ~25°. Dislocations constituting the low-angle boundary are enriched in common (Fe, Zr) and uncommon trace elements (Ca). The Ca is interpreted to be derived from the grain exterior, suggesting diffusion of trace elements along the dislocation cores. The potential for dislocation microstructures to act as fast diffusion pathways must be evaluated when applying traditional geochemical analyses as compositional disturbances caused by the presence of dislocation might lead to erroneous interpretations.</p>

Deconvolution of the composition of fine-grained pyrite in sedimentary matrix by regression of time-resolved LA-ICP-MS data

2020 ◽  
Vol 105 (6) ◽  
pp. 820-832 ◽  
Author(s):  
Aleksandr S. Stepanov ◽  
Leonid V. Danyushevsky ◽  
Ross R. Large ◽  
Indrani Mukherjee ◽  
Irina A. Zhukova
Keyword(s):  
Trace Elements ◽  
Regression Analysis ◽  
Trace Element ◽  
Sedimentary Rocks ◽  
Trace Element Composition ◽  
Element Composition ◽  
Silicate Matrix ◽  
Time Resolved ◽  
Icp Ms ◽  
Wide Range

Abstract Pyrite is a common mineral in sedimentary rocks and is the major host for many chalcophile trace elements utilized as important tracers of the evolution of the ancient hydrosphere. Measurement of trace element composition of pyrite in sedimentary rocks is challenging due to fine-grain size and intergrowth with silicate matrix and other sulfide minerals. In this contribution, we describe a method for calculation of trace element composition of sedimentary pyrite from time-resolved LA-ICP-MS data. The method involves an analysis of both pyrite and pyrite-free sediment matrix, segmentation of LA-ICP-MS spectra, normalization to total, regression analysis of dependencies between the elements, and calculation of normalized composition of the mineral. Sulfur is chosen as an explanatory variable, relative to which all regressions are calculated. The S content value used for calculation of element concentrations from the regressions is calculated from the total, eliminating the need for independent constraints. The algorithm allows efficient measurement of concentrations of multiple chalcophile trace elements in pyrite in a wide range of samples, including quantification of detection limits and uncertainties while excluding operator bias. The data suggest that the main sources of uncertainties in pyrite composition are sample heterogeneity and counting statistics for elements of low abundance. The analysis of regression data of time-resolved LA-ICP-MS measurements could provide new insights into the geochemistry of the sedimentary rocks and minerals. It allows quantification of ratios of elements that do not have reference material available (such as Hg) and provides estimates on the content of non-sulfidic Fe in the silicate matrix. Regression analysis of the mixed LA-ICP-MS signal could be a powerful technique for deconvolution of phase compositions in complex multicomponent samples.

Current issues in trace element nutrition of grazing livestock in Australia and New Zealand

1999 ◽  
Vol 50 (8) ◽  
pp. 1341 ◽  
Author(s):  
D. G. Masters ◽  
G. J. Judson ◽  
C. L. White ◽  
J. Lee ◽  
N. D. Grace
Keyword(s):  
Trace Elements ◽  
New Zealand ◽  
Trace Element ◽  
Recent Work ◽  
Cost Effective ◽  
Trace Element Composition ◽  
Scientific Data ◽  
Pastoral System ◽  
Trace Element Nutrition ◽  
Grazing Livestock

Improving trace element nutrition of grazing animals, in a way that is cost effective and that meets consumer perceptions and preferences, is a continuing challenge. This review focuses on research over the past 10 years, addressing issues and perspectives on the roles, risks of inadequacy, and supplementary remedies of key trace elements, both essential and deleterious, which have an impact on the productivity and product quality of grazing livestock throughout Australia and New Zealand. The emphasis is on copper (Cu), cobalt (Co), iodine (I), selenium (Se), and, to a lesser extent, zinc (Zn) — the trace elements most frequently found to be deficient in parts of Australia and New Zealand. Research continues to elucidate new roles for trace elements in the animal, and as this leads to a better understanding of requirements, diagnostic criteria and supplementation strategies need re-evaluation. Newer perspectives on marginal deficiency for Cu, I, Se, and Zn are given and issues for risk management discussed. Advances in sustained delivery of trace elements such as Co (as vitamin B12), I, and Se are reported. The diagnosis and management of marginal Cu deficiency continue to be difficult, especially in New Zealand where recent work has shown that dietary antagonists [iron (Fe), molybdenum (Mo), and sulfur (S)] may impair Cu absorption at lower intakes than previously thought. There is still a dearth of scientific data on the advantages of using so-called organic trace element supplements (metals complexed or chelated with amino acids or peptides). Nevertheless their usage continues to increase. There is increasing evidence that trace elements influence the pathophysiology arising from the ingestion of toxins. This review summarises recent work on the role of Co in annual ryegrass toxicity; Cu, Se, and Zn in lupinosis; Cu and alkaloid toxicity; Zn and facial eczema; and Co and white liver disease. Trace elements are required to support immune function (e.g. as imposed parasite infection) and marginal deficiencies may be exacerbated by an immunological challenge. The roles of Cu, Co, Mo, Se, and, to a lesser extent, chromium and Zn have attracted attention and under conditions of stress there may be an additional need for these elements. Diversification in farming has led to the introduction of species such as deer (Cervus), alpacas (Camilids), emus, and ostriches (Ratites) and the paucity of information on trace element requirements for these species, and also for horses, indicates the need for further work. The effect of supplementation on trace element composition of meat, milk, and wool is also reviewed, both in terms of product characteristics and human health. Of the deleterious elements, cadmium has attracted the most interest and concern because of its introduction into the pastoral system from phosphate-based fertilisers.

scholarly journals Multivariate Statistical Analysis of Trace Elements in Pyrite: Prediction, Bias and Artefacts in Defining Mineral Signatures

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 61 ◽  
Author(s):  
Marija Dmitrijeva ◽  
Nigel J. Cook ◽  
Kathy Ehrig ◽  
Cristiana L. Ciobanu ◽  
Andrew V. Metcalfe ◽  
...  
Keyword(s):  
Trace Elements ◽  
Statistical Analysis ◽  
Trace Element ◽  
South Australia ◽  
Large Datasets ◽  
Ore Deposits ◽  
Partial Replacement ◽  
Multivariate Statistical ◽  
Wide Range ◽  
Olympic Dam

Pyrite is the most common sulphide in a wide range of ore deposits and well known to host numerous trace elements, with implications for recovery of valuable metals and for generation of clean concentrates. Trace element signatures of pyrite are also widely used to understand ore-forming processes. Pyrite is an important component of the Olympic Dam Cu–U–Au–Ag orebody, South Australia. Using a multivariate statistical approach applied to a large trace element dataset derived from analysis of random pyrite grains, trace element signatures in Olympic Dam pyrite are assessed. Pyrite is characterised by: (i) a Ag–Bi–Pb signature predicting inclusions of tellurides (as PC1); and (ii) highly variable Co–Ni ratios likely representing an oscillatory zonation pattern in pyrite (as PC2). Pyrite is a major host for As, Co and probably also Ni. These three elements do not correlate well at the grain-scale, indicating high variability in zonation patterns. Arsenic is not, however, a good predictor for invisible Au at Olympic Dam. Most pyrites contain only negligible Au, suggesting that invisible gold in pyrite is not commonplace within the deposit. A minority of pyrite grains analysed do, however, contain Au which correlates with Ag, Bi and Te. The results are interpreted to reflect not only primary patterns but also the effects of multi-stage overprinting, including cycles of partial replacement and recrystallisation. The latter may have caused element release from the pyrite lattice and entrapment as mineral inclusions, as widely observed for other ore and gangue minerals within the deposit. Results also show the critical impact on predictive interpretations made from statistical analysis of large datasets containing a large percentage of left-censored values (i.e., those falling below the minimum limits of detection). The treatment of such values in large datasets is critical as the number of these values impacts on the cluster results. Trimming of datasets to eliminate artefacts introduced by left-censored data should be performed with caution lest bias be unintentionally introduced. The practice may, however, reveal meaningful correlations that might be diluted using the complete dataset.

Zinc and Nickel signature for abiogenic and biogenic magnetite: implications for the origin of magnetite in banded iron formations

2020 ◽  
Author(s):  
Xiaohua Han ◽  
Elizabeth Tomaszewski ◽  
Ronny Schönberg ◽  
Yongxin Pan ◽  
James Byrne ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Shewanella Oneidensis ◽  
Transformation Products ◽  
Trace Element Composition ◽  
Trace Element Distribution ◽  
Banded Iron Formations ◽  
Hepes Buffer ◽  
Biogenic Magnetite ◽  
Iron Formations

<p>There are longstanding and ongoing controversies about the abiogenic or biogenic origin of magnetite in banded iron formations (BIFs). The trace element composition of magnetite was proposed as a promising tracer for distinguishing biogenic from abiogenic magnetite, which, however, remains to be explored quantitatively. Here, we compared the partitioning of trace elements Zinc (Zn) and Nickel (Ni) in both abiogenic and biogenic magnetite produced either by an abiotic reaction of ferrihydrite with by Fe<sup>2+</sup><sub>aq</sub> or by Fe(III)-reducing bacteria <em>Shewanella oneidensis</em> MR-1. We compared the transformation of three different ferrihydrite (Fh) starting materials: 1) Control Fh without added trace elements, 2) ferrihydrite with co-precipitated Zn (ZnFh) and 3) ferrihydrite with co-precipitated Ni (NiFh) – both in either NaHCO<sub>3</sub> or HEPES buffer. We monitored Fe concentration and speciation in both aqueous and solid phases over time using the spectrophotometric ferrozine assay, analyzed Fh transformation products by Mössbauer spectroscopy as well as X-ray diffraction and quantified Zn and Ni in solution and in the minerals by iCAP-Qc quadrupole mass spectrometer after acidic dissolution of the minerals. In summary our results revealed that both Zn and Ni are much more depleted in abiogenic magnetite than those in biogenic magnetite, independent of whether magnetite was precipitated in NaHCO<sub>3</sub> or HEPES buffer. Although further analyses are needed, this suggests that the trace element distribution could be a chemical signature to distinguish biogenic from abiogenic magnetite in BIFs.</p>

scholarly journals Mechanisms of deformation-induced trace element migration in zircon resolved by atom probe and correlative microscopy

2016 ◽  
Vol 195 ◽  
pp. 158-170 ◽  
Author(s):  
Steven M. Reddy ◽  
Arie van Riessen ◽  
David W. Saxey ◽  
Tim E. Johnson ◽  
William D.A. Rickard ◽  
...  
Keyword(s):  
Trace Element ◽  
Atom Probe ◽  
Correlative Microscopy ◽  
Element Migration ◽  
Mechanisms Of Deformation

Minor- and trace-element composition of trioctahedral micas: a review

2001 ◽  
Vol 65 (2) ◽  
pp. 249-276 ◽  
Author(s):  
G. Tischendorf ◽  
H.-J. Förster ◽  
B. Gottesmann
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Analytical Data ◽  
Distribution Patterns ◽  
Trace Element Composition ◽  
Element Composition ◽  
Element Partitioning ◽  
Analytical Strategies ◽  
Variscan Granites ◽  
Host Rocks

AbstractMore than 19,000 analytical data mainly from the literature were used to study statistically the distribution patterns of F and the oxides of minor and trace elements (Ti, Sn, Sc, V, Cr, Ga, Mn, Co, Ni, Zn, Sr, Ba, Rb, Cs) in trioctahedral micas of the system phlogopite-annite/siderophyllite-polylithionite (PASP), which is divided here into seven varieties, whose compositional ranges are defined by the parametermgli(= octahedral Mg minus Li). Plots of trace-element contentsvs.mglireveal that the elements form distinct groups according to the configuration of their distribution patterns. Substitution of most of these elements was established as a function ofmgli. Micas incorporate the elements in different abundances of up to four orders of magnitude between the concentration highs and lows in micas of ‘normal’ composition. Only Zn, Sr and Sc are poorly correlated tomgli. In compositional extremes, some elements (Zn, Mn, Ba, Sr, Cs, Rb) may be enriched by up to 2–3 orders of magnitude relative to their mean abundance in the respective mica variety. Mica/melt partition coefficients calculated for Variscan granites of the German Erzgebirge demonstrate that trace-element partitioning is strongly dependent on the position of the mica in the PASP system, which has to be considered in petrogenetic modelling.This review indicates that for a number of trace elements, the concentration ranges are poorly known for some of the mica varieties, as they are for particular host rocks (i.e. igneous rocks of A-type affiliation). The study should help to develop optimal analytical strategies and to provide a tool to distinguish between micas of ‘normal’ and ‘abnormal’ trace-element composition.

scholarly journals Metals composition of the surface waters of the Southern Baikal region and its connection with landscape and geological conditions

2019 ◽  
Vol 486 (5) ◽  
pp. 613-619
Author(s):  
M. Yu. Semenov ◽  
V. A. Snytko ◽  
Yu. M. Semenov ◽  
A. V. Silaev ◽  
L. N. Semenova
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Organic Compounds ◽  
Lake Baikal ◽  
Lake Water ◽  
Trace Element Composition ◽  
Element Composition ◽  
Water Migration ◽  
Element Concentrations ◽  
Geological Conditions

The metal composition of water and bottom sediments of southern Lake Baikal tributaries was studied and the water migration coefficients for micro- and trace elements were calculated. The map showing the study area divided into zones according to their ability to provide the certain water quality was drawn. The significant differences in mineralization, macro- and trace element composition between Lake Baikal water and tributary waters were found out. It was shown that values of water migration coefficients calculated for macro elements are similar in southern and main tributaries whereas coefficient values calculated for trace elements are quite different. This is due to dissolved matter sources such as rocks and deep ground waters which chemical composition is not typical for landscapes of Lake Baikal basin. The contribution of southern tributaries to macro element composition of lake water is between 7 and 15%, whereas tributaries contribution to trace element composition can hardly be evaluated because of higher element concentrations in riverine waters. The lower trace element concentrations in lake water with respect to riverine one is due to trace element migration in the form of complex organic compounds: long water residence time in lake favors to organic compounds decay by means of microbial- and photo-degradation followed by metal precipitation.

scholarly journals Portable X-ray fluorescence (pXRF) calibration for analysis of nutrient concentrations and trace element contaminants in fertilisers

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262460
Author(s):  
Gifty E. Acquah ◽  
Javier Hernandez-Allica ◽  
Cathy L. Thomas ◽  
Sarah J. Dunham ◽  
Erick K. Towett ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Nutrient Concentrations ◽  
Good Prediction ◽  
X Ray ◽  
Accuracy And Precision ◽  
Wide Range ◽  
High Throughput Detection ◽  
Characterisation Methods

With the increasing popularity of local blending of fertilisers, the fertiliser industry faces issues regarding quality control and fertiliser adulteration. Another problem is the contamination of fertilisers with trace elements that have been shown to subsequently accumulate in the soil and be taken up by plants, posing a danger to the environment and human health. Conventional characterisation methods necessary to ensure the quality of fertilisers and to comply with local regulations are costly, time consuming and sometimes not even accessible. Alternatively, using a wide range of unamended and intentionally amended fertilisers this study developed empirical calibrations for a portable handheld X-ray fluorescence (pXRF) spectrometer, determined the reliability for estimating the macro and micro nutrients and evaluated the use of the pXRF for the high-throughput detection of trace element contaminants in fertilisers. The models developed using pXRF for Mg, P, S, K, Ca, Mn, Fe, Zn and Mo had R2 values greater or equal to 0.97. These models also performed well on validation, with R2 values greater or equal to 0.97 (except for Fe, R2val = 0.55) and slope values ranging from 0.81 to 1.44. A second set of models were developed with a focus on trace elements in amended fertilisers. The R2 values of calibration for Co, Ni, As, Se, Cd and Pb were greater than or equal to 0.80. At concentrations up to 1000 mg kg-1, good validation statistics were also obtained; R2 values ranged from 0.97–0.99, except in one instance. The regression coefficients of the validation also had good prediction in the range of 0–100 mg kg-1 (R2 values were from 0.78–0.99), but not as well at lower concentrations up to 20 mg kg-1 (R2 values ranged from 0.10–0.99), especially for Cd. This study has demonstrated that pXRF can measure several major (P, Ca) and micro (Mn, Fe, Cu) nutrients, as well as trace elements and potential contaminants (Cr, Ni, As) in fertilisers with high accuracy and precision. The results obtained in this study is good, especially considering that loose powders were scanned for a maximum of 90 seconds without the use of a vacuum pump.

scholarly journals Detecting trends in freshwater trace element concentrations: methodological issues and data treatment

2018 ◽  
Vol 1 (2) ◽  
pp. 87-98 ◽  
Author(s):  
Juan Carlos Rodríguez-Murillo ◽  
Pascale Nirel ◽  
Montserrat Filella
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Statistical Significance ◽  
Temporal Trends ◽  
Monitoring Program ◽  
Data Treatment ◽  
Wide Range ◽  
Lake Waters ◽  
Program Data ◽  
Difficult Issue

Abstract Despite the fact that the increased use of elements linked to the Anthropocene is frequently assumed to lead to an increase in the concentrations of the elements in surface waters, temporal trends of trace element (TE) concentrations have rarely been checked. A temporally extended, traceable dataset of TE concentrations in the waters of Lake Geneva, Switzerland (1996–2015) has been used here to explore methodological and data treatment issues that arise when attempting to rigorously determine temporal trends in freshwater TE concentrations. The trace elements studied (Cd, Co, Gd, Mo, Pb, Sb, Sr) have been chosen to cover a wide range of chemical and utilisation conditions. We show that detecting temporal trends from monitoring program data is feasible, even when trends are weak, provided that rigorous data treatment methods are applied. Aspects related to the effect of data quality are discussed in detail. However, ascertaining the statistical significance of any trends calculated remains a difficult issue. With the exception of Co and Sr, that show no significant changes, and Pb, that shows a general decrease, concentrations in lake waters of the trace elements considered have increased significantly, particularly between 2006 and 2015.

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