Strontium Research Articles

Microelements, Fatty Acid Profile, and Selected Biomarkers in Grass Carp (Ctenopharyngodon idella) Muscle Tissue: Seasonal Variations and Health Risk Assessment

AbstractThe study assesses associations between microelement levels, fatty acid composition, and oxidative stress markers in grass carp muscle in the summer and autumn seasons. Additionally, various factors were considered, including the estimated daily intake (EDI), target hazard quotient (THQ), total THQ (TTHQ), and metal pollution index (MPI), to evaluate potential health risks for consumers. The microelements (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Ni, Pb, Se, Sr, and Zn) were determined using inductively coupled plasma optical emission spectrometry (ICP-OES), and total mercury was determined using cold-vapor atomic absorption spectroscopy (CV-AAS). Fatty acid profiling was realized using gas chromatography (GC) detection with a flame ionization detector (FID). The overall tendency of microelement levels was as follows: Fe > Zn > Al > Sr > Ba > Ni > Se > Cr> Cu > Mn > Pb > As > Li > Hg; <LOQ (below limit of quantification): Cd, and Co. The correlation analysis between concentrations of trace elements (Al, Ba, Cr, Cu, Mn, Li, Sr, Zn, and Hg) and the fatty acids (C16:0, C16:1, C18:1n9c, C18:2n6c, C20:4n6c, EPA, and DHA), as well as between Al, Ba, Fe, or Hg and oxidative stress markers (superoxide dismutase—SOD, glutathione peroxidase—GPx, or total antioxidant status—TAS), revealed statistically significant interactions in different seasons. THQ values were lower than 1; TTHQ values ranged from 0.27 to 0.76. The main toxic elements forming TTHQ were Hg and Ni (49%). The calculated health risk assessment indices indicate a low concentration of observed elements and low risks associated with the consumption of grass carp muscle from the tested location, although concentrations and THQ of mercury and nickel may be of slight concern.

Excellent energy storage properties and multi-scale regulation mechanism of Sr(Zr0.5Ti0.5)O3-(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics

With the rapid advancement of energy storage technologies, dielectric capacitor materials with the outstanding recoverable energy density and power density have garnered significant attention from researchers in the past decades. In this study, (1-x) (Na0.5Bi0.5)0.94Ba0.06TiO3-xSr(Zr0.5Ti0.5)O3 ceramics were prepared via a solid-state reaction method, and the impact of composition on their structure, energy storage performance and stability were investigated. The results revealed that the introduction of Sr(Zr0.5Ti0.5)O3 induced the ferroelectric-relaxor transformation of (Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics, leading to the destruction of the long-range ferroelectric order and the formation of polar nanoregions. In addition, the 0.7(Na0.5Bi0.5)0.94Ba0.06TiO3–0.3Sr(Zr0.5Ti0.5)O3 ceramic exhibited the optimal comprehensive energy storage performance: its recoverable energy storage Wrec attained 8.19 J/cm3 at 650 kV/cm, while the energy storage efficiency η was 85.6 %. Meanwhile, it displayed exceptionally high power density (315.7 MW/cm3) and charge-discharge rate (t0.9 = 50.4 ns). Moreover, this ceramic demonstrated the impressive energy storage performance, in particular, good temperature stability across a wide range of temperatures (20–140 °C), frequency stability (1–200 Hz), and fatigue resistance (1–106 cycles). Finite element analysis showed an enhancement in the breakdown field strength of the ceramics was attributed to the reduction in grain size. First-principles calculations revealed that the band gap increased after adding Sr and Zr elements, and the interactions between the states of O 2p and Ti 3d, Zr 3d, Bi 6p may serve as the microscopic origin of electron energy level polarization and enhanced dielectric performance. Thus, the ceramics have great potential for the application in high-power pulsed electronic systems.

Structural refinement, dielectric and ferroelectric properties of Cr modified Ba0·90Sr0·10TiO3 ceramics

In this study, we investigated the impact of Chromium substitution on the structural, dielectric and ferroelectric characteristics of Ba0·90Sr0·10Ti1-3x/4CrxO3 (x = 0, 0.005, 0.010, 0.015 and 0.020) ceramics fabricated by solid state reaction method. Rietveld refinement of X-ray diffraction pattern confirmed tetragonal perovskite structure for all the samples. Based on the crystal structure and the lattice parameter obtained through XRD measurement, the Madelung energy of each sample was computed. SEM images revealed a reduction in grain size with rising Cr concentration. TEM, HRTEM, SAED and EDS analysis was carried out for BST-Cr3 sample. Diffused rings observed in Selective Area Electron Diffraction (SAED) patterns indicate the crystallinity of the sample. EDS analysis indicated the presence of Ba, Sr, Ti, O and Cr elements. In the temperature range of 30 °C–150 °C, dielectric measurements (dielectric constant ‘ε’ and tangent loss ‘tanδ’) have been made at different frequencies (1, 10, 50, 100 and 1000 kHz). The samples displayed a diffused phase transition, with noticeable reduction in Curie temperature ‘Tc’ and tangent loss ‘tanδ’ with the substitution of Cr. Polarization versus electric field loops were recorded at different electric fields (5, 10, 15, 20 and 25 kV/cm) and improved values of remnant polarization ‘Pr’ and coercive field ‘Ec’ were observed. A lower Ec value facilitates easier domain movement within the unit cell, leading to enhanced ferroelectric properties. Temperature dependent P-E loops indicated that as the temperature increased, the material became softer accompanied by simultaneous reduction in Pr and Ec values.

SISALv3: a global speleothem stable isotope and trace element database

Abstract. Palaeoclimate information on multiple climate variables at different spatiotemporal scales is becoming increasingly important to understand environmental and societal responses to climate change. A lack of high-quality reconstructions of past hydroclimate has recently been identified as a critical research gap. Speleothems, with their precise chronologies, widespread distribution, and ability to record changes in local to regional hydroclimate variability, are an ideal source of such information. Here, we present a new version of the Speleothem Isotopes Synthesis and AnaLysis database (SISALv3), which has been expanded to include trace element ratios and Sr isotopes as additional, hydroclimate-sensitive geochemical proxies. The oxygen and carbon isotope data included in previous versions of the database have been substantially expanded. SISALv3 contains speleothem data from 365 sites from across the globe, including 95 Mg/Ca, 85 Sr/Ca, 52 Ba/Ca, 25 U/Ca, 29 P/Ca, and 14 Sr-isotope records. The database also has increased spatiotemporal coverage for stable oxygen (892) and carbon (620) isotope records compared with SISALv2 (which consists of 673 and 430 stable oxygen and carbon records, respectively). Additional meta information has been added to improve the machine-readability and filtering of data. Standardized chronologies are included for all new entities along with the originally published chronologies. Thus, the SISALv3 database constitutes a unique resource of speleothem palaeoclimate information that allows regional to global palaeoclimate analyses based on multiple geochemical proxies, permitting more robust interpretations of past hydroclimate and comparisons with isotope-enabled climate models and other Earth system and hydrological models. The database can be accessed at https://doi.org/10.5287/ora-2nanwp4rk (Kaushal et al., 2024).

Potentially toxic trace elements in the muscle of coastal South American fish: Implications for human consumption and health risk assessment

Micropogonias furnieri and Urophycis brasiliensis are two coastal demersal fish species distributed in the southwestern Atlantic Ocean. Considering that many coastal areas in the southwestern Atlantic Ocean suffer from anthropogenic pressure, the aim of this study was to assess the level of potentially toxic trace elements (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, Sr, V and Zn) in the muscle of coastal species, and evaluated the human health risk related to the consumption of muscle. Mercury, inorganic As (Asi), V, and Se showed a higher contribution to the total THQ. Considering two possible scenarios, Asi represents 1 % or 5 % of the total As, the total THQ was <1 for general population and of some health concerns for fishermen population (Total THQ > 1; 5 % Asi). Consequently these results show the importance of quantifying As species in muscle to generate more reliable risk estimates for human health.

Blank sample denoising algorithm (BSDA): An effective spectral noise reduction in water sample LIBS detection

Laser-induced breakdown spectroscopy (LIBS), as an elemental composition analysis technique, has many unique advantages and great potential for applications in water detection. However, the quality of LIBS spectral signals, such as signal-to-noise ratio and stability, is often poor due to the matrix effects of water, limiting its practical performance. To effectively remove the inherent weak radiation in experimental spectral data that can be easily mistaken for noise, this paper proposes a denoising algorithm for processing spectral data using a self-built blank sample spectral database of deionized water samples, and designs a complete data processing workflow. It includes steps such as blank sample data screening, internal standard correction, blank sample correction, and spectral smoothing. Against the backdrop of marine applications, experimental spectral data for target elements Na, Mg, Ca, K, Sr, and Li were processed with this algorithm. The results show that after algorithm processing, the spectral quality was significantly improved, with the signal-to-noise ratio and detection limits of various elements improved by at least one order of magnitude. The signal-for Li increased by up to 36 times, and the detection limit for K decreased by up to 25.2 times. Additionally, tiny spectral peaks that could not be observable in the original spectral data could be effectively extracted after processing. From a technical implementation perspective, the database establishment and data process are simple and practical, with universal applicability. Therefore, this method has good potential and wide foregrounds in many other water sample LIBS detection technologies.

Fractionation Mechanism and Flux Estimation of Strontium Isotopes During Basalt Weathering

AbstractThe fluxes of metal cations and isotopes released by weathering of silicate rocks are crucial and a prerequisite for constraining geochemical fluxes to rivers and oceans. This study presents mineral and elemental compositions along with 87Sr/86Sr and δ88Sr data from a basaltic weathering regolith on Hainan Island, South China to elucidate Sr isotope fractionation and weathering fluxes. The 87Sr/86Sr ratios vary from 0.703936 to 0.706338 as a result of differential weathering of the minerals. δ88Sr values in the weathering regolith range from −0.29 to 0.37‰, with the majority of the weathering regolith having lower δ88Sr values than the parent rock. Sr is leached into the soil solution during plagioclase decomposition, while 86Sr is preferentially adsorbed on the surface of secondary minerals. As weathering progresses, smectite decomposes and kaolinite desorbs under weakly acidic conditions, releasing the previously adsorbed 86Sr into the soil solution. The differential weathering of kaolinite and smectite controls the δ88Sr values of the weathering regolith, with pH being an important determinant of isotope fractionation. Furthermore, Sr elemental fluxes (SrFlux) and Sr isotopic fluxes (δ88SrFlux) of this weathering regolith were calculated using a mass balance model, yielding mean values of 0.20 (mg cm−3 Myr−1) and 0.052 (‰ (mg cm−3 Myr−1)), respectively. The δ88SrFlux exhibits a nonlinear positive correlation with the Chemical Index of Alteration (CIA), indicating that enhanced weathering leads to significant stable Sr isotope fractionation at CIA values below 95%. Our research promotes the understanding of Sr recycling and the fractionation behavior of stable Sr isotopes during consecutive weathering.

Contribution of Asian dust into the sediment budget of the Parece Vela Basin over the last 1 Ma: Implications for the climate change in East Asia

By quantifying the deposition of Asia-derived dust in the Western Pacific Ocean it is possible to constrain the consequences of climate change in East Asia. However, the rates of eolian dust deposition and its transport mechanism in the low-latitude Pacific remain uncertain. Core CP19 recovered sediment dating from ∼1 Ma to the present in the Parece Vela Basin (PVB). In this study we present bulk-rock major and trace element geochemistry, and Sr and Nd isotopic compositions from this sediment. The results reveal that these clastic sediments are a mixture of volcanic materials derived from the adjacent island arcs and eolian dust material originating from the arid regions of East Asia. Within the PVB, the proportion of Asian dust in the detrital sediment ranges from 30% to 50%, with an average of 44%. The majority of the dust originated from Eastern Asian deserts. Sr and Nd isotopes indicate that there is a significant increase in the overall proportion of eolian dust in the PVB starting at ∼0.64 Ma, influenced by an enhanced East Asian winter monsoon. In contrast, strengthening of the East Asian summer monsoon led to a decrease in the proportion of the eolian dust from the Ordos deserts. The notable alteration in eolian dust flux to the PVB corresponds to an abrupt intensification of aridity and monsoon climate in the East Asian continent at ∼0.64 Ma, caused by the Middle Pleistocene Climate Transition.

Petrogenesis of the eudialyte-bearing syenite and indication for Nb-Zr-REE mineralization in Bashisuogong, Northwest China

The Bashisuogong alkaline igneous intrusion is located between the South Tianshan Orogenic Belt and the Kepingtage foreland thrust belt at the northern margin of the Tarim Craton and hosts economically significant Nb–Ta–Zr–rare earth element mineralization. Eudialyte has recently been discovered in the syenite unit of this intrusion, which is the primary host mineral for high-field-strength and rare earth elements. Based on detailed petrographic investigations, this study investigated the behavior of trace elements during magma evolution and the enrichment of ore-forming elements using whole-rock geochemical analyses of eudialyte-bearing syenite and compositional analyses of aegirine–augite and different types of eudialyte. We also undertook in situ titanite UPb dating. The Bashisuogong syenite comprises aegirine–augite and aegirine–augite–eudialyte syenite, the latter of which have higher total rare earth element contents. Both types of syenite exhibit slight enrichments in light rare earth elements, significant enrichments in high-field-strength elements (Nb, Ta, Zr, Hf, and Th), depletions in large-ion lithophile elements (Ba and Sr), and large negative Eu anomalies. There are two types (I and II) of eudialyte. Eudialyte I has higher Mn/Fe, Zr/Hf, and Nb/Ta ratios but lower Th/U ratios compared with eudialyte II but similar Y/Ho ratios. Eudialyte II crystallized earlier than eudialyte I, and aegirine–augite, titanite, and apatite crystallized earlier than eudialyte I. Both aegirine–augite and eudialyte have similar trace element characteristics to the host rocks, exhibiting enrichments in highly incompatible high-field-strength and rare earth elements, as well as marked negative Eu anomalies and depletions in Sr. These characteristics suggest that the Bashisuogong alkaline rocks formed by low-degree partial melting of geochemically enriched, metasomatized lithospheric mantle, which formed an alkaline basaltic parental melt that then underwent protracted magma evolution and fractionation in the shallow crust. The eudialyte syenite yield a titanite UPb age of 277.3 ± 1.2 Ma, which is consistent with the ages of different types of alkaline igneous rocks in the study area, indicating they were the products of the same magmatic event. Temporally and spatially, the Bashisuogong ore-bearing alkaline rocks were associated with the Tarim mantle plume, and the mantle plume provided the heat for their formation.

Application research of monochromatic micro x‐ray fluorescence in glass physical evidence traceability

AbstractMicro‐x‐ray fluorescence (μ‐XRF) is a commonly used elemental analysis technique for glass physical evidence in forensic cases, which can detect major and trace elements in samples and potentially identify glass fragments according to the differences in elemental composition. However, when a sample is irradiated with polychromatic x‐rays, bremsstrahlung scattering from the source radiation provides noise in the fluorescence spectrum and affects the detection results. To improve the signal‐to‐noise ratio of the fluorescence spectrum, a Mμ‐XRF spectrometer constructed under the low‐power Mo target x‐ray tube condition was used to analyze ten kinds of common glass fragments. The application of laboratory Mμ‐XRF analysis in single‐point detection of tiny glass materials was studied. Experimental results show that the detection limit of Sr element was 51 μg/L, and the spectrometer can distinguish different types of small glass fragments according to the fluorescence spectrum information.

Achieving high energy storage performance in PbHfO3-based antiferroelectric ceramics by Sr element doping

Antiferroelectric (AFE) ceramics are the most promising material system for energy storage in dielectric capacitors due to their fast charging-discharging rate, good chemical stability, and high energy storage density. However, it is exceedingly challenging to simultaneously achieve the excellent recoverable energy density (Wre) and high energy storage efficiency (η) at present. In this work, (Pb0.925-xSrxLa0.05)(Hf0.95Ti0.05)O3 AFE ceramics with various Sr contents are fabricated by solid-state sintering processing. It has been found that Sr-doping in the A-site can significantly affect the microstructure, including reducing grain size and modulation period, effectively strengthening the antiferroelectricity, which is responsible for the improved energy storage performance. The high recoverable energy storage density of 10.2J/cm3 is obtained at 560kV/cm with an ultra-high efficiency of 93.0% in (Pb0.875Sr0.05La0.05)(Hf0.95Ti0.05)O3 ceramics. These features suggest that Sr-doped PbHfO3-based AFE ceramics can serve as promising candidates for capacitor materials, offering significant potential in the realm of energy storage applications.

Macro- and Microelements and the Impact of Sub-Mediterranean Downy Oak Forest Communities on Their Composition in Rainwater

In this study, we analyzed the content of chemical elements in rainwater and investigated the influence of forest cover on the composition of precipitation. The results obtained showed that the concentration of some elements in the rainwater collected under the forest canopy was higher than that in the open area. As part of the work, we calculated the enrichment factor and examined the sources of chemical elements in rainwater. We found that all macro-elements had increased values of the enrichment factors compared to the supporting elements of the Earth’s crust. Ca had the highest value. The values of the remaining elements (Sr, Pb, Mn, Cr, Ba, V, Fe) indicated their lithogenic and anthropogenic origins. We noted that the enrichment factor under the forest canopy was significantly lower than in the open area, indicating the dilution of these elements during water passage through the canopy. Elements such as Zn, Co, Cu, and Ni also had high enrichment factors, which indicate their anthropogenic origin. In the open area, most elements had an inverse relationship with pH, except for the alkali metals Na, Mg, and Ca, which had a positive relationship with the pH value. The concentration of K was not dependent on pH. In rainwater that had passed through the forest canopy, the concentrations of Na, Mg, and Ca were also not dependent on pH, while the concentration of K had an inverse relationship with pH. As the concentration of heavy metals in rainwater increases, the role of Na, Mg, and Ca in the process of water neutralization decreases.

Hydroclimate variability over the past 4730 years based on multi-proxy stalagmite records from southwest China

Southwest China has experienced a series of record-breaking droughts over the last two decades, threatening regional ecosystems and exerting socioeconomic effects. Recent studies have focused on the drivers of specific drought events that seasonally vary in occurrence and duration, and a better understanding of regional paleo-records may be key to understanding their underlying mechanisms. Here, we present records of dry and wet alterations from 4730 yr B.P. based on multi-proxy stalagmite records. In particular, we report δ13C records at a five-year-resolution, and trace element (Mg, Sr, and Ba) to Ca ratios at a 25-year-resolution for stalagmite HD12 from Dark Cave, southwest China. Statistically significant correlations between δ13C and Mg/Ca suggest that they are controlled by a common factor, possibly related to local hydrological variations associated with the monsoon circulation. Long-term trends in the Sr/Ca and Ba/Ca ratios may be related to temperature- and/or precipitation-controlled growth rates. The first principal component (multi-proxy PC1) of δ13C and Mg/Ca can be used as the hydrological index in southwest China, indicating high-frequency oscillations on the millennial to multidecadal scales, with four prominent dry periods at 4255 ± 21 to 3430 ± 11, 2605 ± 12 to 2105 ± 9, 1755 ± 11 to 1255 ± 13, and 705 ± 8 to 405 ± 7 yr B.P. This is in general agreement with the monsoon index reconstructed from the detrended and z-scored cave δ18O PC1 in southwest China, indicating the sensitivity of regional hydrological response to monsoon intensity. The dry conditions of southwest China on the millennial-centennial scale may be related to solar forcing and the North Atlantic Oscillation owing to their influence on the strength and position of the westerlies and the Intertropical Convergence Zone. Additionally, the El Niño Southern Oscillation could also affect water vapor transport to southwest China by influencing the strength and position of the Walker circulation and Western Pacific Subtropical High. Moreover, the dry periods of southwest China over the past 4730 years are closely related to the warming of the sea surface temperature of the tropical warm pool on multidecadal scales. Such warming may be detrimental to the transport of water vapor from the North Western Pacific and Indian Ocean to southwest China, resulting in a dry regional environment.

Quantitative profiling and baseline intervals of trace elements in healthy lung tissues

BackgroundHuman lung tissue, as an interface with the environment, is susceptible to various environmental pollutants, including trace metals. However, quantitative data on trace metals in human lung tissues remain poorly described. MethodsThis study aimed to characterize the elemental composition of histologically healthy, unaffected parts of human lung tissues, associated with non-infective, non-infiltrative, and non-malignant diseases (n = 60) for essential (Cr, Mn, Fe, Co, Cu, Zn, and Se) and toxic trace elements (Sr, Ni, As, Cd, and Pb). Additionally, we investigated the influence of personal factors (sex, age, and smoking habits) on the examined trace element profiles, as well as between the trace elements correlations in the healthy human lungs. ResultsAmong the analyzed trace elements, Fe was the most prevalent, while As was the least prevalent in healthy lung tissues. Stratifying by age revealed significantly higher Cr and Co (less Sr, Ni, and Pb) and lower Se levels in older individuals (above 65 years) compared to their younger counterparts. Sex-based differences were also notable, with Cu and Co 1.2- and 2.3-fold higher levels in females than in males. Exploring the impact of smoking habits revealed a striking 10-fold increase in Cd levels in the lung tissues of smokers compared to non-smokers. Correlation analyses showed significant positive associations between concentrations of certain toxic and essential trace elements in healthy lung tissues. ConclusionsThis study could contribute to the establishment of baseline intervals for essential and toxic trace elements, valuable for toxicological and clinical assessment, in healthy, unaffected human lungs, and indicates the influence of sex, age, and smoking. However, further larger-scale studies are needed to make more stable conclusions.

Combined use of principal component analysis/multiple linear regression analysis and artificial neural network to assess the impact of meteorological parameters on fluctuation of selected PM2.5-bound elements.

Based on the data of the State of Global Air (2020), air quality deterioration in Thailand has caused ~32,000 premature deaths, while the World Health Organization evaluated that air pollutants can decrease the life expectancy in the country by two years. PM2.5 was collected at three air quality observatory sites in Chiang-Mai, Bangkok, and Phuket, Thailand, from July 2020 to June 2021. The concentrations of 25 elements (Na, Mg, Al, Si, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Sr, Ba, and Pb) were quantitatively characterised using energy-dispersive X-ray fluorescence spectrometry. Potential adverse health impacts of some element exposures from inhaling PM2.5 were estimated by employing the hazard quotient and excess lifetime cancer risk. Higher cancer risks were detected in PM2.5 samples collected at the sampling site in Bangkok, indicating that vehicle exhaust adversely impacts human health. Principal component analysis suggests that traffic emissions, crustal inputs coupled with maritime aerosols, and construction dust were the three main potential sources of PM2.5. Artificial neural networks underlined agricultural waste burning and relative humidity as two major factors controlling the air quality of Thailand.

Structural and Compositional Changes in Two Marine Shell Traditional Chinese Medicines: A Comparative Analysis Pre- and Post-Calcination.

Arcae concha and Meretricis concha cyclinae concha are two marine shellfish herbs with similar composition and efficacy, which are usually calcined and used clinically. This study investigated variations in the inorganic and organic components of Arcae concha and Meretricis concha cyclinae concha from different production regions, both Arcae concha and Meretricis concha cyclinae concha. The aim was to enhance the understanding of these two types of marine shell traditional Chinese medicine (msTCM) and provide a foundation for their future development and application. Spectroscopic techniques, including infrared spectroscopy, X-ray spectroscopy, and X-ray fluorescence spectroscopy, were used to analyze the calcium carbonate (CaCO3) crystal and trace elements. Thermogravimetric analysis was used to investigate the decomposition process during heating. The proteins were quantified using the BCA protein assay kit. Principal component analysis (PCA) was used to classify inorganic elements in the two marine shellfish traditional Chinese medicines. No significant differences among the various production regions. The crystal structure of CaCO3 in the raw products was aragonite, but it transformed into calcite after calcination. The contents of Ca, Na, Sr, and other inorganic elements were highest. The protein content was significantly reduced after calcination. Therefore, these factors cannot accurately reflect the internal quality of TCM, rendering qualitative identification challenging. CaCO3 dissolution in the decoction of Arcae concha and Meretricis concha cyclinae concha increased after calcination, aligning with the clinical application of calcined shell TCM. PCA revealed the inorganic elements in them, indicating that the variation in trace element composition among different drugs leads to differences in their therapeutic focus, which should be considered during usage. This study clarified the composition and structure changes of corrugated and clam shell before and after calcining, and laid the foundation for the comprehensive utilization of Marine traditional Chinese medicine. These technical representations reveal the differences between raw materials and processed products, which will provide support for the quality control of other shellfish TCMS.

Tectonic dismemberment and plume-ridge interaction in the Sub-Antarctic South Atlantic Ocean Basin: Confirmation from in situ geochemical and Sr isotopic compositions of minerals

The Sub-Antarctic South Atlantic Ocean has been inferred to have undergone a complex tectonic history involving dismemberment and plume-ridge interaction. Here we report new in situ major (electron probe microanalysis, EPMA), trace element (laser ablation−inductively coupled plasma−mass spectrometry, LA-ICP-MS), and Sr isotopic (laser ablation−multicollector−inductively coupled plasma−mass spectrometry, LA-MC-ICP-MS) compositions for minerals (olivine, clinopyroxene, and plagioclase) from the Northeast Georgia Rise (NGR; Sites 698 and 699), Islas Orcadas Rise (IOR; Site 701), and Meteor Rise (MR; Site 703) volcanic samples in the Sub-Antarctic South Atlantic Ocean. Plagioclases and clinopyroxenes from Sites 698, 699, and 703 are characterized by similar incompatible element patterns and Sr isotopic characteristics, suggesting that they are likely to have originated from a cogenetic mantle source. The plagioclases and clinopyroxenes exhibit an oscillatory, reverse, and normal zoning texture, and display clear evidence of Sr isotopic disequilibrium, suggesting dynamic and open fractional-crystallization processes as well as extensive mixing of compositionally distinct magmas. Rims and groundmass of plagioclase exhibit much more highly radiogenic Sr isotopes than their cores, likely indicating the involvement of both continental lithospheric and recycled oceanic crust. The in situ geochemical and isotopic compositions of these minerals exhibit the features of both the oceanic-island basalt−type Tristan-Gough mantle plume track and the normal mid-oceanic-ridge basalt−type Mid-Atlantic spreading ridge (MAR) and Agulhas spreading ridge (AR) track. We speculate that the NGR, IOR, and MR were formed from the same mantle source with volcanic flow of the Tristan-Gough mantle plume. Subsequently, tectonic movement along the MAR and AR separated the originally combined MR-IOR-NGR, resulting in the incursion of depleted asthenospheric mantle and the contamination contributions of continental and recycled oceanic crust components.

Carbonate metasomatism in sub-continental lithospheric mantle: Insights from decoupled Nd[sbnd]Hf isotopes of Mesozoic gabbros in Jinan, eastern North China Craton

The ancient sub-continental lithospheric mantle (SCLM) of the eastern North China Craton (NCC) underwent metasomatism in the Triassic due to fluids derived from subducted Yangtze continental crust, followed by further metasomatism during the Jurassic–Cretaceous caused by fluids originating from subducted Paleo-Pacific oceanic slabs. However, the occurrence of carbonate metasomatism during these two geological events is a subject of debate, and the origin of carbonate-bearing metasomatic agents remains ambiguous. Here, we present an integrated study of petrography, whole-rock trace element data and Sr–Nd–Hf–Pb isotope data for the Jinan gabbros in the Luxi block of the eastern NCC. The Jinan gabbros show arc-like trace element patterns and enriched Sr–Nd–Hf–Pb isotopic compositions, suggesting that they originated from partial melting of the enriched ancient SCLM. In addition, there are remarkable similarities in Sr–Nd–Hf–Pb isotopes between the Jinan gabbros and HP–UHP metamorphic rocks in the Dabie–Sulu orogenic belt, indicating the involvement of continental crustal components from the subducted Yangtze block in the mantle source of the Jinan gabbros. The gabbro samples show decoupled NdHf isotopes with positive ∆εHf values (∆εHf = εHf – 1.55 × εNd – 1.21; Vervoort et al., 2011), which were mainly caused by a metasomatic agent with high Nd/Hf ratios. The increase in εNd values with increasing Hf/Hf* (Hf/Hf* = HfPM/[(NdPM × SmPM)0.5]) and Nb/La further indicates that the metasomatic agent in the mantle source was depleted in high field strength elements (HFSEs) but enriched in rare earth elements (REEs), resembling the mantle-derived carbonatites in the Luxi area. The Jinan gabbros show significant variations in εNd and εHf, which cannot be explained by the involvement of C–O–H fluids and pure carbonatitic melts in their mantle source. Instead, carbonate-bearing felsic melts from the deeply subducted Yangtze continental crust are proposed to have acted as metasomatic agents. Carbonate metasomatism can significantly weaken the strength and decrease the melting temperature of the overlying ancient SCLM. Therefore, carbonate metasomatism that occurred in the lithospheric mantle of the eastern NCC during the Triassic, likely associated with deep subduction of the Yangtze block, might have played a significant role in promoting lithospheric thinning and mafic magmatism in the late Mesozoic.

On the formation of Al2Si2Sr phase and its behavior in Al–Si–Sr alloys

Sr element is commonly used to modify eutectic Si in Al–Si alloys, while Al2Si2Sr phase is quite easy to precipitate when Sr content is high to tens of ppm level. In this study, the growth models of Al2Si2Sr crystal as well as its behavior in Al–xSi–2 Sr (x=5, 8, 12, 18, 25 and 40, wt%) alloys were investigated. Polyhedral, triangular pyramid and dendritic morphologies of Al2Si2Sr crystals were detected, and their growth models were discussed. Based on the crystallographic parameters, the disregistry between (0001)Al2Si2Sr and (111)Si is calculated to be 9.7%. Transmission electron microscopy analysis confirms that the Al2Si2Sr phase is not likely to be a good nucleation site for Si. Differential scanning calorimetry analysis indicates that Al2Si2Sr phase is firstly precipitated in Al–5, 8, 12, 18Si–2 Sr alloys, while its precipitating temperature is close to primary Si in Al–25Si–2 Sr alloy and it falls behind to primary Si in Al–40Si–2 Sr alloy. Interestingly, amounts of Al2Si2Sr dendrites were engulfed by primary Si in Al–40Si–2 Sr alloy. Based on the widely–known impurity–induced twinning mechanism in Sr modified Al–Si alloys, the Al2Si2Sr dendrites were deduced to be in–situ evolved from Sr–rich clusters, which are absorbed on {111}Si planes. This work may provide a new perspective for understanding the modification mechanisms of Sr element on Si crystal in Al–Si–Sr alloys.

A two-stage process of alkali fusion and organic acid leaching for recovery of critical elements from coal fly ash

Coal fly ash (CFA) is a promising alternative source for critical elements. Most of the critical elements in CFA are associated with the aluminosilicate glassy phase, which hinders their ability to solubilize during acid leaching. In this study, critical elements (Li, Be, Rb, Sr, Zr, Nb, Cs, Hf, Ta, Ga, Ge, Se, Cd, and Tl) were recovered from CFA of Pingwei power plant in China by alkali fusion-organic acid leaching. The results showed that the leaching rate of critical elements after alkali fusion was higher than that of direct organic acid leaching. The leaching rate of total critical elements was 72.56% under the optimal conditions. Among them, the highest leaching rate of Li, Be and Ga was more than 90%, and the highest leaching rate of Ge, Se, Rb, Sr, Zr, Nb, Cd, Cs and Hf was 70%-90%. Characterization analysis revealed that the amorphous aluminosilicate and silica phases in the raw CFA were destroyed by alkali fusion, resulting in nepheline and soluble aluminosilicate phases which were easily dissolved by citric acid. This study provides theoretical basis and technical support for the extraction of critical elements from CFA.