Low Zn Concentrations Research Articles

Effect of combined addition of Zr, Ti and Y on microstructure and tensile properties of an Al-Zn-Mg-Cu alloy

Composite micro-alloying is an important technique for developing cost-effective, high-performance aluminum alloys. Here, the effect of combined addition of Zr, Ti and rare-earth Y on the microstructure and tensile properties of an Al-7.6Zn-1.6 Mg-2.1Cu (wt.%) alloy is systematically investigated by means of X-ray diffraction, optical microscopy, scanning electron microscopy, transmission electron microscopy and room-temperature unixal tensile tests. After adding 0.12 %Zr, 0.04 %Ti and 0.28 %Y, L12-Al3Zr/(Al,Zn)3Zr, AlMgZnTiCuFe and (Al,Zn)8Cu4Y phases were induced; the as-T6 treated microstructure of the base alloy changed from fully recrystallized to fully unrecrystallized, accompanied by strong 〈100〉 + 〈111〉 fiber textures along extrusion direction. As a result, the Al-Zn-Mg-Cu-Zr-Ti-Y alloy with low Zn and Mg contents exhibits an ultimate tensile strength of 692 MPa, yield strength of 647 MPa (∼36 % higher than the base alloy) and 6.8 % elongation. The main strengthening mechanisms responsible for this high yield strength are Orowan dislocation bypassing strengthening (∼449 MPa), fiber texture strengthening, and dispersion strengthening. Moreover, the synergistic strengthening effect of rare-earth Y and transitional element(s) Zr and/or Ti was revealed, which may be related to the formation(s) of nanoscale network-structured Al8Cu4Y and/or L12-Al3(Zr,Y) phase(s). The massive formation of the Al8Cu4Y network structure requires a narrow process window.

The role of nanofiltration modelling tools in the design of sustainable valorisation of metal-influenced acidic mine waters: The Aznalcóllar open-pit case

Acid Mine Waters (AMWs) are considered the most challenging environmental problem in the Iberian Pyrite Belt (South of Spain) so far, being characterised by an acidic pH (H2SO4-based), high content of heavy metals (e.g. Co, Pb, rare earth elements (REEs)) and non-metals (e.g. As). Nowadays, AMWs are being contemplated as a source of valuable metals (e.g. Zn, Cu, REEs), and different recovery routes have been studied (e.g. ion-exchange, membrane technologies). Among them, nanofiltration (NF) provides the possibility of water (or H2SO4) recovery and concentration of metals, which can be recovered in a subsequent stage. This work evaluates the performance of the Desal DK NF membrane to treat AMW from Aznalcóllar open-pit, which presents a low pH (2.6) and high contents of Zn (920 mg/L), Mg (2540 mg/L) and REEs (17 mg/L). The effect of solution pH on membrane performance was evaluated. Results showed that the equilibrium SO42-/HSO4- controlled the transport of species. Rejections of sulphate were around 84 % at pH 2.1 (prevalence of HSO4-) and increased to 92 % at pH 3.1 (prevalence of SO42-). Metal rejections remained higher than 74 % (except for monovalent species). Additionally, membrane permeances were determined using the Solution-Electro-Diffusion model coupled with reactive transport, and later used to assess the design of the process treatment of the AMW. Results demonstrated the possibility of concentrating metals and recovering H2SO4 as permeate, but also showed that gypsum and anhydrite precipitation can occur. Additionally, CAPEX and OPEX were estimated for a NF plant treating 2 Hm3/year.

Facile biosynthesis of ZnO/attapulgite nanocomposite for enhanced antimicrobial performance

• ZnO/APT nanocomposite was synthesized by a facile green one-pot protocol. • APT assisted forming of small sized ZnO NPs by offering rich nucleation sites. • ZnO NPs were formed by a bioreduction process without further thermal treatment. • Nanocomposite exhibited enhanced antibacterial activity and low cytotoxicity. An attapulgite (APT) supported ZnO nanocomposite (ZnO/APT) was developed through a facile green protocol mediated by Ginkgo biloba leaf extract. ZnO nanoparticles in the 5–10 nm size range, which were much smaller than pure ZnO particles, were uniformly decorated on APT surface, leading to an enhanced antibacterial performance of ZnO/APT nanocomposite compared with pure ZnO and the mixture of ZnO and APT. Moreover, the nanocomposite showed low cytotoxicity on L-O2 due to the green process and low Zn content. The obtained nanocomposite will be applicable in the medical field due to its safety and good performance.

Enhanced recovery of zinc and lead by slag composition optimization in rotary kiln

High-efficiency recovery of Zn and Pb from silicon-rich zinc leaching residues is realized in a rotary kiln. Characterizations by means of XRD, SEM, EDS and ICP reveal that the leaching residue contains 12.4 wt.% SiO2, 16.1 wt.% Zn, and 7.4 wt.% Pb. Thermodynamic analysis shows that metallic vapor of Zn and Pb can be easily generated from the zinc leaching residue at 1150−1250 °C inside the rotary kiln. Viscosities and melting points of 13 slag compositions were analyzed and three slag compositions (47wt.%SiO2−23wt.%CaO−30wt.%FeO, 40wt.%SiO2− 28wt.%CaO−32wt.%FeO, and 40wt.%SiO2−30wt.%CaO−30wt.%FeO) possessed the desirable physical properties, with the melting point and viscosity in the range of 1150−1280 °C and 0.2−0.5 Pa·s, respectively. The industrial tests show that adopting the optimized slag composition can contribute to very high recovery rates of Zn and Pb (97.3% for Zn and 94.5% for Pb), corresponding to slags with very low average contents of Zn and Pb (0.51 wt.% Zn and 0.45 wt.% Pb). The National-Standard leaching tests of the water-quenched slags result in 1.82 mg/L Zn, ~0.01 mg/L Cu, 0.0004 mg/L As, ~0.01 mg/L Cd, 0.08 mg/L Pb, and ~0.02 mg/L Hg in the leachate, verifying the detoxification of the zinc leaching residue at the same time.

Effect of Zn substitution on the AC induction heating properties of ZnxMn1-xFe2O4 (x = 0.1–0.9) nanoparticles prepared using microwave assisted synthesis

ZnxMn1-xFe2O4 (x = 0.1–0.9) magnetic nanoparticles (MNPs) were prepared using a microwave-assisted coprecipitation method, and the effect of Zn substitution on the AC induction heating properties of the MNPs was investigated. With increasing Zn substitution, owing to the lower solubility product of Zn2+ ions, the formation of new nuclei was preferred over grain growth, which reduced the average crystallite size. The saturation magnetization initially increased with Zn substitution, attained the maximum value at x = 0.5, and decreased beyond that due to Yafet-Kittel type triangular spin ordering. The prepared MNPs exhibited superparamagnetic behaviour at ∼ 300 K. AC induction heating studies of the MNPs indicated a specific absorption rate of ∼ 130 ± 4 W/gFe at x = 0.1. The AC induction heating efficiency did not exhibit any non-monotonic variation at x = 0.5, and progressively decreased with increasing Zn concentration. This was attributed to the reduction in the MNP size and anisotropy energy density at higher Zn concentration that caused the relaxation dynamics to be Nèel dominated with lower effective relaxation time. AC induction heating studies on the agar-immobilized samples confirmed the Brownian relaxation mediated magneto-thermal energy conversion at lower Zn concentration. The obtained results demonstrated that saturation magnetization alone does not influence the AC induction heating efficiency and relaxation dynamics play a significant role.

Diversity and composition of soil bacteria between abandoned and selective-farming farmlands in an antimony mining area.

Background and aimsLand abandonment and selective farming are two common management methods to restore the soil conditions of low-pollution farmland in mining areas. The soil bacterial community plays an important role in farmland soil restoration; however, few studies have compared the composition and diversity of soil bacteria between the abandoned farmlands (AFS) and selective-farming farmlands (FFS). Here, the effects of AFS and FFS on soil properties and bacterial diversity were evaluated in an antimony (Sb) mining area in southern China. This study aimed to identify effective land management methods in terms of positive or negative changes in soil environment and bacterial diversity.Methods16S rRNA high-throughput sequencing was used to compare the diversity and composition of soil bacteria between AFS and FFS in the Xikuangshan (the largest Sb mine in the world).ResultsCompared to AFS, FFS had higher Sb concentration and nutritional properties (e.g., available N, P, and K) and lower Zn concentration (p < 0.05). The bacterial alpha diversity including Chao1 index, Simpson index, Shannon index and Pielou−e index in FFS was higher than AFS (p < 0.05). At the phylum level, FFS had higher relative abundances of Chloroflexi, Acidobacteria, Gemmatimonadetes, and Rokubacteria, and lower relative abundances of Firmicutes, Actinobacteria, and Bacteroidetes. At the genus level, FFS had higher relative abundances of Acidothermus, Haliangium, and Rokubacteriales, and lower relative abundances of Bacillus, Rhodococcus, Sphingomonas, and 67-14. Redundancy analysis indicated that soil heavy metal content and soil fertility were closely correlated with the soil bacterial community. Altogether, selective farming of low-pollution farmland in the mining area can improve soil properties and soil bacterial diversity.

Microstructure and precipitation behaviours of laser clad 7075 aluminium alloy

Laser cladding is a promising technique for repairing metal components. However, the extreme thermal conditions introduced by laser heat can lead to complex precipitation behavior in the cladding layer and heat-affected zone (HAZ). In this paper, the laser cladding technique was applied to repair a widely used aircraft structural material - 7075 aluminium alloy. Specimens of the cladding layer, HAZ, and their interface were site-specifically prepared by using focused ion beam (FIB) and micro-manipulator. The microstructure and precipitation behaviours of these regions were characterized individually using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the cladding layer forms various species of precipitates, such as coarse MgZn2 particles, Zn-rich particles, and CuMgZnAl compounds. Coarse inclusions and voids are formed at the interface between the cladding layer and HAZ. In the HAZ, solute redistribution and re-precipitation take place due to the laser heating cycle. The majority of Mg and Zn atoms segregate at grain boundaries in the HAZ, resulting in low Mg and Zn contents in the grain interior. The number density of nano-particles was significantly reduced in the HAZ, compared to the unaffected 7075 aluminium alloy substrate, which explains the strength reduction in the HAZ.

Agronomic Biofortification of Zinc in Rice for Diminishing Malnutrition in South Asia

Zinc (Zn) is increasingly recognized as an essential trace element in the human diet that mediates a plethora of health conditions, including immune responses to infectious diseases. Interestingly, the geographical distribution of human dietary Zn deficiency overlaps with soil Zn deficiency. In South Asia, Zn malnutrition is high due to excessive consumption of rice with low Zn content. Interventions such as dietary diversification, food fortification, supplementation, and biofortification are followed to address Zn malnutrition. Among these, Zn biofortification of rice is the most encouraging, cost-effective, and sustainable for South Asia. Biofortification through conventional breeding and transgenic approaches has been achieved in cereals; however, if the soil is deficient in Zn, then these approaches are not advantageous. Therefore, in this article, we review strategies for enhancing the Zn concentration of rice through agronomic biofortification such as timing, dose, and method of Zn fertilizer application, and how nitrogen and phosphorus application as well as crop establishment methods influence Zn concentration in rice. We also propose data-driven Zn recommendations to anticipate crop responses to Zn fertilization and targeted policies that support agronomic biofortification in regions where crop responses to Zn fertilizer are high.

Comparative study of pomelo‐peel‐derived hydrochar and torrefied poultry‐litter on coal fuel blends: Combustibility, synergy factor, and ash analysis

AbstractCo‐firing is considered to be a promising approach for the reduction of CO2 emissions from coal‐fired plants. However, the utilization of fruit‐waste‐based feedstocks is less common than the use of animal‐waste feedstocks, which are usually accompanied by high toxic ash content and low combustibility. In this work, pomelo‐peel‐derived hydrochar (PPHC), characterized by excellent fuel properties and combustibility, was systematically compared with torrefied poultry litter (PLBC), to promote its use as an eco‐friendly solid fuel. The two bio‐based solid fuels were prepared using hydrothermal carbonization (180–240 °C) and torrefaction (220–310 °C), respectively. Elemental analysis, proximate analysis, scanning electron microscopy, Brunauer–Emmett–Teller (BET) analysis, and Fourier‐transform infrared (FTIR) spectroscopy were used to study the physicochemical and structural properties of the prepared chars. The combustion behavior and post‐combustion ash content of PPHC/coal and PLBC/coal blends were assessed by thermogravimetric analysis (TGA) and X‐ray fluorescence (XRF). Fuel blends of PPHC and coal showed superior combustibility (S = 5.77–14.79 × 10−12), stronger synergistic effects (1.48–3.19°C−3 min−1/2), and lower activation energy requirements (28.5–31.6 kJ mol−1), in comparison with PLBC/coal blends. Comparative analysis of heavy metal content revealed that PPHC/coal blends were characterized by less toxicity, with lower concentrations of Fe, Mn, Zn, Cu, As, and Co. Hence, the results demonstrated that pomelo peel hydrochar, with excellent combustibility and environmental friendliness, could serve as a better alternative for co‐firing with coal. Meanwhile, torrefied poultry litter showed undesirable ash properties, suggesting an urgent need for the development of alternative methods for its treatment. © 2022 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Use of limpets as alternative to mussels in metal pollution monitoring; application in the Canary Islands

Metal pollution monitoring programs make use of organisms, such as mussels, as biomonitors to evaluate and compare the metal pollution status of coastal areas worldwide. Despite the widespread distribution of mussels of the genus Mytilus, there are places where these organisms are absent or where their abundance is insufficient for biomonitoring purposes, such as in the Canary Islands (Spain). This study considers the use of limpets of the genus Patella as alternative/complementary species in metal pollution monitoring, and compares the bioaccumulation capacity of mussels and limpets collected simultaneously during several sampling campaigns at 11 sampling sites along the continental Spanish Atlantic coastline. Results show that there are some differences in bioaccumulation capacity between limpets and mussels, with limpets showing in average higher concentrations of Cd, Cr, Ni, As and Cu, and lower concentrations of Zn, while concentrations of Hg and Pb were similar for both types of organisms. Significant correlations between metal concentration in mussels and limpets were found for most metals, with the notable exception of Cd, that showed a very different bioaccumulation pattern in both types of organisms. Limpet to mussel metal concentration ratios were derived that can be used to compare the results of metal biomonitoring using either limpets or mussels, and limpets were successfully used in a monitoring survey in the Canary Islands.

Invited Review: Assessing trace mineral status in ruminants, and factors that affect measurements of trace mineral status

The purpose of this article is to review criteria for assessing copper, zinc, manganese, and selenium status in ruminants. Factors that affect measurements of trace mineral status also will be discussed. Published scientific literature was the primary source of information reviewed. When assessing mineral status, it is always good to analyze the diet or forages being consumed for the mineral of interest as well as other minerals that may affect its requirement. Liver is the best indicator of both low and excess Cu status. Plasma Cu concentrations do not decrease below normal values until liver Cu stores are mostly depleted, but a plasma Cu concentration less than 0.4 mg/L suggests Cu deficiency. Severe Zn deficiency can be diagnosed based on extremely low plasma or serum Zn concentrations (less than 0.5 mg/L) or on clinical signs of Zn deficiency that respond to Zn supplementation. It is important to note that infections or acute stress may cause plasma Zn concentrations to temporarily decrease to levels consistent with Zn deficiency. There is currently no reliable indicator of marginal Zn deficiency. Several criteria have been measured in an attempt to assess Mn status. However, no criteria have been demonstrated to accurately predict Mn deprivation. Whole blood or liver Se concentrations are useful in assessing Se status. When interpreting whole blood or liver Se concentrations, it is important to consider whether dietary Se is being derived from organic or inorganic sources. The most appropriate measurement criteria to assess trace mineral status in ruminants depend on the trace mineral being considered. Liver copper is generally a good measure of low as well as excess Cu status. Liver or whole blood Se concentrations are reliable measures of Se status if one takes into account the source of dietary Se. Unless clinical deficiency signs are apparent, it is more difficult to assess Zn and Mn status. In the absence of disease or stress, plasma or serum Zn concentrations below 0.5 mg/L suggest possible severe deficiency. No reliable predictor of marginal Zn deficiency has been determined. Currently, no reliable indicator of Mn status has been identified.

Development of a novel tailored ion-imprinted polymer for recovery of lithium and strontium from reverse osmosis concentrated brine

This study aims to prepare ion-imprinted polymer (IIP) with the benefit of a metal-based sorbent, which is fabricated to selectively adsorb lithium (Li+) from aqueous solutions, and in an attempt to remove strontium (Sr2+). The adsorption processes were carried out at different pH values, initial concentrations, and temperatures, to optimize the experimental conditions, with the use of response surface methodology (RSM). The seawater reverse osmosis (SWRO) brine was physically and chemically characterized, and the physicochemical characterization of the prepared IIP before and after adsorption was also performed using different spectroscopic methods. The adsorption capacity for Li+ and Sr2+ from SWRO brine was evaluated, and the reusability of IIP was investigated using adsorption–desorption cycles. The results showed that the IIP was efficient to remove Li+ but not Sr2+, and it follows Freundlich adsorption isotherms models. The analysis revealed a significant concentration of minerals in the brine sample It also revealed a low concentration of trace metals, like Ba (0.16 mg/L), Zn (0.845 mg/L), Fe (1.31 mg/L), Cu (1.165 mg/L), Pb (1.505 mg/L), and V (3.88 mg/L), except Li and Sr which shows a higher concentration of 43.32 mg/L and 16.93 mg/L respectively. pH 10 was selected to be the optimum pH for the adsorption isotherm experiments, as it was the highest efficient pH to adsorb Li+ and Sr2+. The thermodynamics study revealed that the adsorption of Li+ on the IIP favored exothermic conditions. It was noticed that the maximum adsorption capacity (Qm) was increased as the temperature rise from 714.3 mg/g at 25 °C to 2500 mg/g at 45 °C. The Li+ desorption results show that 94.03% − 94.71% of the ions were recovered, while the Sr2+ desorption results show that 96.35% − 96.56% of the ions were recovered. The efficiency of IIP to adsorb lithium and strontium from brine shows that the adsorption removal% of Li+ was between 84.21% and 84.68%, while the adsorption removal% of Sr2+ was between 3.83% and 10%. The cost analysis for IIP preparation was 2 USD/g.

Biomass Quality Variations over Different Harvesting Regimes and Dynamics of Heavy Metal Change in Miscanthus lutarioriparius around Dongting Lake

Miscanthus lutarioriparius has a growing area of 100,000 ha and an annual biomass production of 1 Mt around Dongting Lake. However, due to serious soil pollution, there is a concern that the M. lutarioriparius biomass could have high heavy metal (HM) concentrations. This necessitates investigation of biomass quality to find the appropriate end use. Thus, this study aims to investigate the dynamics of HM elements in the M. lutarioriparius biomass and their impact on biomass quality across different growing areas and harvest times. We analyzed the HM concentrations in soil and biomass from 11 sites under different harvesting times (April, August and December). Results showed that Cd in soil samples was 9.43-fold higher than the national standards. The heavily polluted soil caused a high HM concentration in the biomass and the accumulation increased with the delayed harvest. The fresh young shoots in April met the food limitation for Cd and Cr, whereas Pb concentration was slightly higher than the threshold limit. The mature biomass from the southern part had higher Mn, Cd and Pb, but lower Cu, Zn and Cr concentrations than that from the eastern part. These results can provide guidance for guaranteeing the consistent quality of the M. lutarioriparius biomass for bio-based industry.

Albumin-corrected Zn and available free Zn-binding capacity as indicators of Zn status – potential for clinical implementation

We have established and describe two measurement procedures to diagnose possible zinc (Zn) deficiency; albumin-corrected Zn concentration and available free Zn-binding capacity. Reference intervals for both biomarkers were established in healthy adults from the Danish population. The clinical usefulness of the measurement procedures was investigated in patients with cirrhosis and in patients given parenteral nutrition due to short bowel syndrome. The results of both methods indicate that there is a risk of overdiagnosing Zn deficiency based on low plasma Zn concentrations. Needless Zn supplementation may thus be avoided by using the albumin-corrected Zn concentration or available free Zn-binding capacity.

Foliar Application of an Inositol-Based Plant Biostimulant Boosts Zinc Accumulation in Wheat Grains: A μ-X-Ray Fluorescence Case Study.

There has been much interest in the incorporation of organic molecules or biostimulants into foliar fertilizers with the rationalization that these compounds will enhance the uptake, or subsequent mobility of the applied nutrient. The objective of this research was to investigate the effects of an inositol-based plant stimulant on the mobility and accumulation of foliar-applied zinc (Zn) in wheat plants (Triticum aestivum L.). High-resolution elemental imaging with micro-X-ray fluorescence (μ-XRF) was utilized to examine Zn distribution within the vascular bundle of the leaf and whole grains. The inclusion of myo-inositol with Zinc sulfate, significantly increased Zn concentration in shoots in contrast to untreated controls and Zn sulfate applied alone. Foliar Zn treated plants increased Zn in grains by 5–25% with myo-inositol plus Zn treated plants significantly increasing grain Zn concentration compared to both Zn treated and non-treated controls. XRF imaging revealed Zn enrichment in the bran layer and germ, with a very low Zn concentration present in the endosperm. Plants treated with Zn plus myo-inositol showed an enhanced and uniform distribution of Zn throughout the bran layer and germ with an increased concentration in the endosperm. While our data suggest that foliar application of myo-inositol in combination with Zn may be a promising strategy to increase the absorption and mobility of Zn in the plant tissue and subsequently to enhance Zn accumulation in grains, further research is needed to clarify the mechanisms by which myo-inositol affects plant metabolism and nutrient mobility.

Anthropogenic Zn contamination dispersion in Sepetiba Bay evidenced by Zn isotopes

Sedimentary processes in coastal environments play a key role in the spatial dispersion of metal contaminants, including Zn. Combining Zn stable isotope signatures (δ66Zn) with traditional proxies of sedimentary sources and dispersal and post-depositional processes is a promising approach to understanding Zn anthropogenic dynamics in coastal systems that remains untested. To this end, we coupled geochemical and isotope tools to infer sedimentary contributions on Zn fate and behavior in surface sediments of Sepetiba bay, a tropical lagoon in Rio de Janeiro state chronically contaminated by an old stake of electroplating wastes Zn-enrich. Our results show high variability in δ66Zn values (0.43‰ to 0.89‰) and Zn enrichment factors (1 to 23-fold), evidencing a gradient in mixing sedimentary sources. The biplot δ66Zn versus 1/[Zn] highlights that the Zn isotope variability of most samples fell within a mixing source trend involving natural Zn (+0.29‰, 67 mg.kg-1) and anthropogenic Zn (+0.89‰, 3,440 mg.kg-1), the latter attributed to the Sepetiba bay’s historical Zn metallurgical contamination. Based on the isotope mixing model and geochemical proxies (e.g., Ti/Al ratio), we calculated that Zn excess in the Sepetiba Bay varies from 42% to 98%. The Zn enrichment distribution across the bay confirmed anthropogenic Zn dispersal from the Saco de Engenho, mainly controlled by the clock direction water current. Sediments mineralogical composition and correlations between Zn isotope and Al concentrations indicate that the high content of anthropogenic Zn is associated with silt and clay sediment particles composed of gibbsite and clay minerals such as kaolinite and organic matter. Our findings demonstrate that combining Zn isotope ratios with other geochemical proxies may help pinpoint Zn anthropogenic origins and behavior as well as track its dispersion in the land-sea continuum. In this case, this approach provides more accurate results on Zn contamination dispersion in the Sepetiba Bay and avoids possible misleading interpretations concerning anthropogenic Zn origins at low Zn concentration levels.

Zn-clays in the Kihabe and Nxuu prospects (Aha Hills, Botswana): A XRD and TEM study

Abstract Zinc clays are commonly found in oxidized Zn deposits and, even though they rarely represent the main target of the ore exploitation, they can be used as a proxy to restore the genetic conditions during ore-forming processes. This work sheds light on the micro- to nano-mineralogy and on the genesis of Zn-clays in the Kihabe and Nxuu prospects (located in the Aha Hills district, Northern Botswana), through an integrated XRD and TEM study of the mineralized facies occurring in the ore system. The Kihabe and Nxuu ores are hosted in a Neoproterozoic metamorphozed quartzwacke unconformably covered by the recent sedimentary rocks, also containing calcretes, of the Kalahari Group. In the analyzed samples, four distinct mineralogical facies have been recognized: (1) vanadate-calcrete facies, poor of Zn-clays; (2) low Zn-clay facies, characterized mostly by clays showing low Zn concentrations; (3) Zn-clay facies, containing proper Zn clay minerals; and (4) sulfide facies, devoid of Zn-clays. In all the facies detrital dioctahedral mica (muscovite and illite) is interstratified with smectite in the form of random (R0) to short-range ordered (R1) I/S, which locally shows significant Zn concentrations. In the sulfide facies kaolinite overgrowing onto mica packets has been detected. The low Zn-clay facies is dominated by Zn-bearing beidellite, with minor kaolinite and fraipontite. The Zn-clay facies consists mostly of a random (R0) interstratified clay between a 7 Å phase corresponding to fraipontite, and a 2:1 swelling clay component identifiable with the dioctahedral smectite, with minor sauconite. The micro- to nano-scale paragenetic study performed by TEM indicates that the above-mentioned clays formed through a multistage process, eventually ending with the genesis of Zn-bearing phyllosilicates assemblages. The main steps were: (1) alteration of detrital mica and dissolution of feldspar clasts, which led to the formation of epitaxial kaolinite and replacive beidellite; (2) fertilization of barren clays and formation of replacive to epitaxial fraipontite/smectite and of Zn-bearing mica, through input of Zn2+ deriving from sphalerite or willemite dissolution by mixed meteoric-hydrothermal fluids; (3) formation of low tetrahedral charge sauconite, either in pores or as replacement of K-feldspars under surficial hypersaline conditions, possibly also linked to the establishment of the arid climate in region. These processes provide insights into genesis of Zn-Pb-V ore deposits in northwest Botswana. Furthermore, the identification of a Zn-smectite species having a stevensite-like stoichiometry is valuable for future studies dealing with the systematics of clay minerals.

Elemental Profiles of Legumes and Seeds in View of Chemometric Approach

The study aimed to evaluate fourteen elements’ profiles of legumes and oilseeds, of various geographical origins, available on the Polish market. They were determined by flame atomic absorption spectrometry (F-AAS) and spectrophotometric method (phosphorus) in 90 analytical samples. In general, legumes were characterized with lower mean concentrations of Ca, Mg, Na, P, Zn, Cu, Fe, Mn, and Cr than oilseeds. However, the concentrations ranges within each group differed significantly (p &lt; 0.05). Calcium content varied between 6.2 and 243.5 mg/100 g in legumes and 38.4 and 2003 mg/100 g in oilseeds. In the case of Fe, its concentration was between 1.99 mg/100 g and 10.5 mg/100 g in legumes, and 2.05 mg and 12.15 mg/100 g in seeds. All the samples were characterized with Pb concentration below the LOQ (30 µg/100 g). In the case of Cd, its presence (&gt;LOQ, 9 µg/100 g) was confirmed in one sample of legumes (soybean) and five samples of seeds (poppy seeds, roasted linseeds, hulled wheat, linseed, and sunflower seeds). The detected Cd content in every sample, except for soybean and hulled wheat, exceeded the permissible European standards. According to Kruskal-Wallis test results, Mg, Na, K, P, Zn, Cu, Mn, Cr, and Cd content depended on the type of the analyzed product, while in the case of botanical provenance such relationship was recorded for most of the analyzed components, except for Fe, Cr, and Co. Factor and cluster analyses classified the analyzed samples in view of their botanical species and type based on their mineral composition.

Geographical distribution of trace elements (selenium, zinc, iron, copper) and case fatality rate of COVID-19: a national analysis across conterminous USA.

Severe outcome particularly death is the largest burden of COVID-19. Clinical observations showed preliminary data that deficiency in certain trace elements, essential for the normal activity of immune system, may be associated with worse COVID-19 outcome. Relevant study of environmental epidemiology has yet to be explored. We investigated the geographical association between concentrations of Se, Zn, Fe and Cu in surface soils and case fatality rate of COVID-19 in USA. Two sets of database, including epidemiological data of COVID-19 (including case fatality rate, from the University of John Hopkinson) and geochemical concentration data of Se, Zn, Fe and Cu in surface soils (from the National Geochemical Survey), were mapped according to geographical location at the county level across conterminous USA. Characteristics of population, socio-demographics and residential environment by county were also collected. Seven cross-sectional sampling dates, with a 4-week interval between adjacent dates, constructed an observational investigation over 24 weeks from October 8, 2020, to March 25, 2021. Multivariable fractional (logit) outcome regression analyses were used to assess the association with adjustment for potential confounding factors. In USA counties with the lowest concentration of Zn, the case fatality rate of COVID-19 was the highest, after adjustment for other influencing factors. Associations of Se, Fe and Cu with case fatality rate of COVID-19 were either inconsistent over time or disappeared after adjustment for Zn. Our large study provides epidemiological evidence suggesting an association of Zn with COVID-19 severity, suggesting Zn deficiency should be avoided.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10653-022-01204-0.

Zinc isotope evidence for carbonate alteration of oceanic crustal protoliths of cratonic eclogites

Zinc isotopic compositions (δ66ZnJMC-Lyon) of low-MgO (<13 wt.%) and high-MgO (>16 wt.%) eclogites from the Koidu kimberlite complex, Sierra Leone, West African Craton, help constrain the origins of cratonic eclogites. The δ66Zn of low-MgO eclogites range from MORB-like to significantly higher values (0.21‰ to 0.75‰), and correlate inversely with Zn concentrations. Since marine carbonates are characterized by higher δ66Zn and lower Zn concentration than basaltic rocks, the low-MgO eclogites are suggested to originate from altered oceanic crustal protoliths that underwent isotopic exchange with carbonates within the crust during subduction. Compared to low-MgO eclogites, all but one of the high-MgO eclogites also have high δ66Zn (0.35‰ to 0.95‰), but they have lower Zn concentrations and Zn/Fe ratios, both of which are negatively correlated with MgO contents. These features point to formation of high-MgO eclogites via metasomatic overprinting of low-MgO eclogites through addition of secondary clinopyroxenes crystallized from infiltrating ultramafic melts. Thus, both low-MgO and high-MgO eclogites bear the imprint of subducted carbonate-bearing oceanic crust. Our study shows that the distinctively high-δ66Zn signatures of marine carbonates can be retained in deeply subducted oceanic crust that may contribute to mantle sources of intraplate alkali basalts with elevated δ66Zn and Zn/Fe. Therefore, Zn isotopes provide a viable means to trace carbonate recycling in the mantle.