Coupled trace element and Hf-isotope measurements of Hadean through Paleoarchean zircons from the Singhbhum Craton indicate derivation from a long-lived, mantle-derived protocrust

Due to the dearth of rock records during the Hadean, little is known about early crustal chemistry and geodynamics. Here, we present zircon trace and rare earth element and Lu-Hf measurements of zircons ~ 3.3 Ga to ~ 4.2 Ga from the Older Metamorphic Tonalitic Gneiss in the Singhbhum Craton to better understand geodynamic changes during the Hadean and Archean. We find decreasing, subchondritic zircon εHfT among zircons > 3.8 Ga and no indication of addition of new crustal material during the Hadean after initial formation of this protocrust. Trace and rare earth element analyses of >3.8 Ga grains indicate derivation from a source heavily influenced by the enriched mantle with little evidence for flux melting, and no clear evidence for deep melting. At ~ 3.8 Ga, we observe an average εHfT increase indicating new additions of juvenile material. These zircons still show predominantly mantle-like trace elements, but with the appearance of some arc-like trace element zircon signatures and evidence for crustal thickening. This period of crustal reorganization speaks towards a shift in geodynamic regime characterized by the onset of communication between the mantle and the crust from which the zircons formed at this location. The presence of long-lived, mantle-derived protocrust in both India and South Africa appears to suggest the possibility of a stagnant lid, albeit more data is necessary to confirm this. The presence of a transition of εHfT data globally may point towards an important period of crustal reorganization 3.9 – 3.6 Ga ago.

This review of the literature from 2004 and 2005 concerning secondary ion mass spectrometry (SIMS) highlights the contribution the technique has made in the fields of petrology, geochronology, cosmochemistry and material sciences. In petrology, much research was devoted to the measurement of stable isotopes and trace elements by developments in multicollection acquisition, with emphasis on low atomic mass number elements. Elements studied in particular were S (in sulfides), O (in garnets), C (in sedimentary organic matter), Cl (in glasses) and Si. Novel applications of SIMS to geochronology have included the measurement of young zircon grains by the U‐Pb and U‐Th decay methods. An increasing number of studies have combined U‐Pb geochronology with the measurement of trace elements or stable isotopes in zircon.

Trace element equilibrium in acute heart failure and the effect of empagliflozin.

BackgroundThis study is focused on the measurement of trace elements (zinc, copper, cadmium, lead and selenium) in the saliva of pigs in order to study their levels on different porcine pathological conditions in the field. The experiment involved 15 pigs without clinical signs of disease and 42 diseased pigs (suffering from lameness, rectal prolapse, fatigue or growth rate retardation). Individual saliva samples were collected, allowing the pigs to chew a sponge each for trace element quantifications through atomic absorption spectrometry (AAS). Since this is the first report on the measurements of trace elements in porcine saliva, a routine analytical validation study was performed for the quantification of all the studied elements. Moreover, the acute phase proteins C-reactive protein (CRP) and haptoblobin (Hp), the total antioxidant capacity (TAC) and adenosine deaminase (ADA) were quantified in the saliva samples for the animal’s health status assessment.ResultsModifications in the levels of acute phase proteins or ADA were only recorded in animals with lameness and rectal prolapse and those with fatigue respectively. Moreover, TAC level changes were observed in pigs with growth-rate retardation. However, alterations in the levels of two or more trace elements were reported for all the different groups of diseased pigs with evident variations within pathologies.ConclusionsThe salivary quantification of trace elements could be considered as a complementary tool to acute phase proteins, TAC and ADA determinations for disease detection and differentiation in the pig and should be explored in greater depth.

The results of research during FY 1976, FY 1976A, FY 1977, and FY 1979 under terms of the Interagency Energy/Environment Agreement are summarized. Trace element studies have been centered around the coal-fired Four Corners Power Plant located on the Navajo Reservation in northwestern New Mexico, which forms an integral part of the energy-rich Colorado Plateau region. The overall objective of this research has been to assess environmental consequences of trace elements identified as potentially hazardous to arid western ecosystems. To this end the two major corollary goals are to: (1) identify potentially hazardous trace elements in stack emissions and assess their importance with respect to deposition onto surrounding terrain, and (2) to determine which elements are mobilized in the scrubber system and ash disposal ponds at the Four Corners Power Plant. Results of dry deposition calculations, trace element measurements in air particulate, soils, and vegetation are reported pursuant to the first goal. Trace elements extracted from fly ash, trace element measurements in influent and effluent waters of the power plant, and trace element concentrations in a specie of vegetation growing in these effluent water channels are reported pursuant to the second goal.

In situ trace element analysis of melt inclusions by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) provides important geochemistry information. However, the precision and accuracy of this technique are affected by many factors, such as matrix effect, laser conditions, and calibration method. In addition, many previous LA-ICP-MS studies ablated entire melt inclusions along with their host minerals and obtained trace element composition by deconvoluting the mixed ablation signal, which may induce much uncertainty. A 193 nm ArF laser ablation system combined with inductively coupled plasma sector field mass spectrometry (ICP-SF-MS) was used to investigate matrix effect, laser conditions, choice of external calibration standards, and data reduction strategy for in situ analysis of 36 major and trace elements in six common silicate reference glasses. The validity of the protocol presented here was demonstrated by measuring trace elements in olivine-hosted melt inclusions. Instead of ablating entire melt inclusions along with their host minerals, melt inclusions were polished to the surface to avoid laser ablating the mineral host. The calibration lines calculated from the calibration standards should cross the coordinate origin, especially for low-concentration elements (<10 ppm). As the laser crater size increased from 17 to 33 μm, the precision was improved from <20% to <8% (2RSD), and accuracy was improved from ±20% to better than ±10%. Most measured trace elements in Dali melt inclusions are consistent with those in their host rocks. For mobile elements (Ba, Sr, Pb), melt inclusions display much smaller variations than their host rocks. A simple but accurate approach for in situ analysis of trace elements in melt inclusions by LA-ICP-SF-MS has been established, which should greatly facilitate the wider application of in situ trace element geochemistry to melt inclusion studies.

A variety of biomarkers are available for the assessment of human exposure to, and absorption of, trace elements. The measurement of trace elements in nail or nail clippings offers some benefits relative to other body sites. Typically, concentrations of elements are assessed in clippings, using high precision methods such as inductively coupled plasma mass spectrometry or instrumental neutron activation analysis. Over the last decade, portable X‐ray fluorescence (pXRF) has emerged as a novel method with potential advantages for the measurement of trace elements in nail and nail clippings. This review paper examines early developments and recent work in the use of pXRF to measure elements such as As, Se, Mn, Zn, Cr, Pb, and Hg in nails and nail clippings. While initial pXRF studies were limited to the use of nail phantoms and nail clipping phantoms, more recent work has applied the pXRF method with real nail clippings and nails. Results have been promising, but a number of issues have emerged requiring additional attention. These relate to the analysis of X‐ray spectra, selection of X‐ray beam for excitation, method validation and normalization, and practical aspects of study design. With consideration of these issues, pXRF offers significant potential to provide a straightforward, economical, and rapid measurement approach to help improve our understanding of trace element exposure and related health outcomes.

Chemical contamination assessment of the Hudson–Raritan Estuary as a result of the attacks on the World Trade Center: Analysis of trace elements

The concentration of 12 elements (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) has been investigated in the feathers of three species of Ardeidae, namely the Grey Heron Ardea cinerea, the Little Egret Egretta garzetta, and the Cattle Egret Bubulcus ibis, all breeding at a colony located in the southern Padana Plain (NW Italy). This study is a first step for an evaluation of possible direct effects of these elements on chicks’ survival and growth rate. Fe, Zn, Cu, and Mn were in the range 7–69 mg Kg−1, while lower levels of Pb, Ni, As, and Se (0.27–1.45 mg Kg−1) were measured. Co, Cd, and Cr were close to the method detection limits (MDLs) in all the species. The measured concentrations of the most abundant trace elements, such as Zn and Cu, seem to reflect the geochemical pattern of the background (running water and soil), while Hg concentration is lower and it appears to be biomagnified, particularly in Grey Heron feathers. Its concentration is higher in adults than in chicks, and it differs among the three species, as it is closely related to the fish-based dietary pattern. The measured trace elements’ concentrations are below the threshold levels in all the heron species, and consequently, harmful and acute effects on the local population are unlikely; the conservation status of herons populations in northern Italy is probably more affected by other factors, such as climate changes, altered aquatic environment, and, consequently, food quality.

Tar and trace element measurements in synthesis gas from a pressurized black liquor gasifier.

BackgroundTrace elements exhibit essential functions in many physiological processes. Thus, for research focusing on trace element homeostasis and metabolism analytical methods allowing for multi-element analyses are fundamental. Small sample amounts may be a big challenge in trace element analyses especially if also other end points want to be addressed in the same sample. Therefore, the aim of the present study was to examine trace elements (iron, copper, zinc, and selenium) in murine liver tissue prepared by a RIPA buffer-based lyses method. Methods and resultsAfter centrifugation, lysates and pellets were obtained and trace elements were analyzed with TXRF in liver lysates. The results were compared to that obtained by a standard microwave-assisted acidic digestion with subsequent ICP-MS/MS analysis of the same liver tissue, liver lysates, and remaining pellets. In addition, trace element concentrations, determined in murine serum with both methods, were compared. For serum samples, both TXRF and ICP-MS/MS provide similar and highly correlating results. Furthermore, in liver lysate samples prepared with RIPA buffer, comparable trace element concentrations were measured by TXRF as with the standard digestion technique and ICP-MS/MS. Only marginal amounts of trace elements were detected in the pellets. ConclusionTaken together, the results obtained by the present study indicate that the RIPA buffer-based method is suitable for sample preparation for trace element analyses via TXRF, at least for the here investigated murine liver samples.

Trace element abundances in rutiles from eclogites and associated garnet mica schists

Measurement of trace elements in post-mortem human visceral and subcutaneous adipose tissues

Background: The concentration of trace elements and metals in the thyroid is the result of exposure, uptake, retention, and clearance. The specificity and selectivity of thyroid capacity to concentrate these elements relative to other tissues are not known. To obtain this information, we measured the tissue concentration of 26 elements in the thyroid, muscle, and fat of euthyroid human subjects and also in normal rats. Methods: At programmed surgery, small (<1 g) tissue fragments were collected in 77 euthyroid subjects. Macroscopically normal thyroid tissue, sternothyroid muscle, and neck subcutaneous fat samples were excised, and thyroid tissue was confirmed to be morphologically normal through microscopy. Tissue specimens (thyroid, hindlimb muscle, and abdominal fat) were also obtained from normal rats. Measurements of trace elements were performed on tissues using inductively coupled plasma mass spectrometry (DRC-ICP-MS). Results: Only 19 of the 26 investigated elements were measurable as 7 elements were below the limit of detection. The ranking concentration in human thyroid tissue, not considering iodide, indicated that Zn, Br, Cu, Cr, Se, and Mn represented over 95% of the measured elements. A similar ranking was observed in the rat thyroid. A comparison with other tissues indicated that in addition to I, also Br, Mn, Se, and Sn were significantly more concentrated in the thyroid, and this was also the case for the recognized carcinogens As, Cd, and Hg. As and Hg, but not Cd (which was not detectable in any of the rat tissues), were also more concentrated in the rat thyroid. Since human thyroid specimens were also obtained from residents of a volcanic area, where environmental pollution may cause human biocontamination, we compared the trace element concentration in specimens from the volcanic area with controls. Many trace elements were slightly, but not significantly, increased in the volcanic area specimens. Conclusions: In the normal human thyroid, many trace elements, including Br, Mn, Se, and Sn, and the recognized carcinogens, As, Cd, and Hg, are significantly more concentrated than in muscle and fat of the same individual. Similar data were observed in rats. The reason for the differential element accumulation in the thyroid is unclear; a better understanding may be useful to further clarify thyroid biology.

The pressure-temperature location of garnet and spinel lherzolite facies boundary is often critical for understanding mantle dynamics. We have investigated the boundary by experiments using natural starting materials. For compositions close to the model primitive mantle at constant temperature of 1360°C, garnet-in boundary is approximately 2.3 GPa while spinel-out is at approximately 2.6 GPa. The redistribution of trace elements during the garnet break down reaction (i.e. olivine[ol] + garnet[gt] = orthopyroxene[opx] + clinopyroxene[cpx] + spinel[sp]) lags behind phase equilibrium and product opx and cpx “inherit” the REE abundances from reactant garnet. Diffusion equilibration for trace elements takes several hundred thousand years for pyroxenes over distance of 500µm at 1200°C. The pressure-temperature data for garnet-spinel transformation are inadequate particularly under near solidus conditions in natural peridotite compositions. Previous experimental studies have demonstrated that compositional effects on the location of garnet-spinel facies boundary in simple systems were considerable (e.g. Nickel, 1986; O’Neill, 1981). Addition of chrome shifts the boundary to higher pressures, but the data are not sufficient for extrapolating the results to natural compositions. For natural systems, experimental studies of the transformation boundary are limited in number (Jenkins and Newton, 1979; O’Hara et al., 1971) and their results span over a range approximately 10 kbar. Furthermore, experimental results for the transformation boundary near solidus (above 1300°C) do not exist. Our experiments were aimed at determining where garnet and spinel become stable at near solidus condition (e.g. 1360°C). In addition, the phase rule predicts a range of pressure- temperature conditions for the existence of transitional garnet-spinel lherzolite zone, because the degree of freedom is more than two for the garnet break down reaction in the natural system. This suggests that the garnet-in boundary is located toward the lower pressures than the spinel-out boundary. We circumvent the problem, that is caused by sluggishness of reaction, by monitoring rates of the garnet breakdown and growth reactions. Model parameters corresponding to chemical affinity are determined from time dependent progresses of the reaction. These parameters are used to extrapolate the condition where reaction rate is zero, that is equilibrium. The results show that at 1360°C garnet-in boundary is located at 0.3 GPa lower pressure than spinelout boundary. Garnet and spinel can coexist in the range of pressure. It should be noted that the 0.3 GPa pressure range for the coexistence is difficult to resolve by the conventional reversal reaction method (Koga et al., 1998). Trace elements that reside in garnet have to be redistributed during the garnet break-down reaction. Peridotite samples that have experienced the decompression often display incomplete trace element redistribution in newly formed minerals. Trace element measurements on experimental charges demonstrate that product opx and cpx “inherit” the trace element abundance from the reactant garnet, and there are no recognizable differences in abundance of trace element between opx and cpx. Thus, while major element abundances in pyroxenes are in equilibrium as demonstrated by experimentally calibrated geothermobarometers, trace element redistribution is incomplete. This may be caused by the differences in diffusivities of major and trace elements. The disequilibrium trace element distribution similar to experimental results could be expected in rocks under went rapid decompression. Indeed, The trace element distribution among fine grained rims around garnet consisting opx, cpx, and spinel in peridotite xenoliths from Lashaine, Tanzania closely resembles experimental results. Time scales for equilibration of pyroxenes can be modeled by diffusion. A model involving a spherical grain with a constant composition boundary, and a model with adjacent finite length slabs of opx and cpx, are compared under various diffusivities and boundary conditions in cooling histories. The results show persistence of disequilibrium for 7-800k years at high temperature (1200°C), and fractionated zoning of rare earth elements due to D(Yb) > D(La). Starting materials are mineral separates from garnet lherzolite from Pali Aike, Chile for garnet break down and spinel lherzolite from Kilbourne Hole, USA for garnet production reaction. Experiments are conducted at the conditions at 1360°C and from 1.8 to 3.0 GPa, with the run duration spanning form 2 to 200 hours. The run conditions were achieved by 2.54 cm diameter piston-cylinder type apparatus, with Ba- CO3 as pressure transmitting medium. Pressure calibrations were done by the CaTs break-down reaction (Hays, 1967) and An-Sp lherzolite transformation for CMAS system at subsolidus and above solidus conditions (Kushiro and Yoder, 1966). Volume fractions of product phases are measured from the digitally captured back-scattered electron images with the combination of x-ray images. Major element compositions are measured by electron probe. Trace elements abundances are measured by ion probe.