Low Iron Content Research Articles

Water scaling predication for typical sandstone geothermal reservoirs in the Xi'an Depression

The Xi'an Depression in the Guanzhong Basin of western China has been suggested to contain geothermal resources that could aid China in achieving carbon neutrality and optimizing energy structure. However, the high concentration of total dissolved solids (TDS) and scale-forming ions in geothermal water from the depression causes severe scaling problems in harvesting geothermal energy. To reduce scale-related problems, accurate identification of scale types and prediction of scaling during geothermal energy utilization are crucial. This study starts with identifying the types and trends of scaling in the study area, using index-based discriminant methods and hydrogeochemical simulation to calculate and analyze the mineral saturation index of water samples from some wellheads and of reconstructed fluid samples of geothermal reservoirs. The results indicate that the scales are mostly calcium carbonate scales rather than sulfate scales as a result of temperature changes. Several portions of the geothermal water systems are found to have distinct mineral scaling components. Quartz and chalcedony are formed in low temperature areas, while carbonate minerals are in high temperature areas. Despite the low iron content of geothermal water samples from the study area, scaling is very common due to scaling-prone iron minerals. The findings can be used to evaluate geothermal drainage systems and guide anti-scaling during geothermal energy utilization in similar settings.

High Soil pH and Plastic-Shed Lead to Iron Deficiency and Chlorosis of Citrus in Coastal Saline–Alkali Lands: A Field Study in Xiangshan County

Citrus are one of the most important fruit crops in the world, and the citrus hybrid cv. Beni-Madonna (BM) is widely cultivated in Xiangshan County in China because of its profitability. However, due to the lack of technical guidance and management, nutritional unbalances of trees occur frequently and are a major constraint for fruit quality and yield. In this study, the soil and fruit nutritional status of 62 citrus orchards in three diverse landforms (mountain, flat, and coastal saline–alkali land) located in Xiangshan County has been investigated. Higher pH, calcium, and magnesium content but lower soil organic matter, nitrogen, iron, and boron content were observed in orchards of the coastal saline–alkali land compared with the mountain and flat lands. Compared to Citrus x unshiu, another major hybrid citrus cultivar in Xiangshan county, the Fe deficiency in fruits of BM in coastal saline–alkali lands was more severe, leading to chlorosis symptoms. In addition, long-term cultivation under plastic housing increased soil salinization and affected the absorption of Fe and other nutrients by BM. In conclusion, organic fertilizers, acidic fertilizers, and micronutrient fertilizers should be applied in citrus orchards located in coastal saline–alkali lands. Especially, BM orchards should be supplemented with iron fertilizer and not rely excessively on protection with plastic films.

Investigating the sustainable performance of a nanoscale zerovalent iron permeable reactive barrier for removal of nitrate, sulfide, and arsenic

Abstract The quality of groundwater resources is at catastrophic risk. The proper performance of iron nanoparticles has made a permeable reactive barrier (PRB) an alternative to conventional filtration methods. The performance of nanozerovalent iron (nZVI) PRBs is limited by particle aggregation, instability, and phase separation, even at low iron concentrations. Therefore, the precipitation of reactive materials and a decrease in the longevity of PRB are fundamental challenges. A laboratory setup is used to compare the performance of bare nZVI and xanthan gum (XG)-nZVI + Mulch PRB to simultaneously remove nitrate, sulfide, and arsenic in groundwater. nZVI (average diameter of 35–55 nm) particles are used as reactive media. The objectives are (1) to develop a method for treating nitrate, sulfide, and arsenic simultaneously in groundwater using organic mulch and XG-nZVI; and (2) to evaluate the longevity performance of the XG-nZVI + Mulch and bare nanoparticles treatment system over 10 days. The results showed that the XG-nZVI + Mulch barrier's performance for eliminating NO3-, As, and S2− was generally improved compared to the bare nZVI barriers by 5.7, 19.2, and 10.9%, respectively. Finally, despite the need for long-term sustainability assessment, XG-nZVI PRB performance is impressive, and this stability promises to improve the longevity of nanoparticles while used in PRBs.

Serum concentration of zinc, copper, iron, and its associated factors among pregnant women of small-scale farming in western Ethiopia

Micro-nutrients are required in small amounts to maintain growth and cell functioning to complete the life cycle through reproductions. However, pregnant women in developing countries like Ethiopia are vulnerable to multiple micro-nutrient deficiencies. Therefore, this study aimed at assessing the serum level of metals and associated factors like dietary diversity, and health-related problems in pregnant women among small-scale farming in Kellem Wellega, western Ethiopia. A cross-sectional laboratory-based study was conducted from June to August 2021 on 417 pregnant women attending antenatal care at rural healthcare facilities. Data was collected by using per-tested structured questionnaires via face-to-face interviews. The data analysis was conducted using SPSS version 24.0, and multivariate logistic regression analysis was performed to determine the association between predictor and outcome variables. A statistically significant was considered at p value < 0.05 for all the analyses. Our study findings showed that 62.1, 80.9, and 71.9% of the participants were deficient in iron, zinc, and copper micro-nutrient levels, respectively. Pregnant women who could not have formal education were 3.24 (AOR = 3.24, 95% CI 1.33–7.91) and 3.98 (AOR = 3.98, 95% CI 1.2–13.15) times more likely to show zinc and copper deficiency than those who attended secondary school and above, respectively. Furthermore, pregnant women involved only in farming activities were 0.57 (AOR = 0.57, 95% CI 0.36–0.91) and 4.33 (AOR = 5.72, 95% CI 2.34–13.97) times more likely to be exposed to iron and zinc deficiency than those who were engaged in other activities. This study revealed that pregnant women with low income were 6.36 times more likely to be exposed to zinc micro-nutrient deficiencies than those with high-income participants (AOR = 6.36, 95% CI 1.47–27.61). Additionally, those participants who ate a varied diet between 1 and 4 items per day were 2.26 (AOR = 2.26, 95% CI 1.43–3.59) and 2.77 (AOR = 2.77, 95% CI 1.6–4.61) times more likely to suffer zinc and copper micro-nutrient insufficiency than those who consumed 5–10 items per day. Finally, pregnant women who developed diarrhea in the past three months were 1.82 (AOR = 2.77, 95% CI 1.14–2.92) and 2.52 (AOR = 2.52, 95% CI 1.3–4.91) times more likely to be exposed to iron and copper deficiency than those who never show the symptoms, respectively. This study identified low concentrations of zinc, iron, and copper in the blood serum of pregnant women of small-scale farmers.

Sex differences in cadmium and lead concentrations in different biological matrices in athletes. Relationship with iron status

PurposeThe present study aimed to analyse sex differences in cadmium and lead concentrations in plasma, urine, platelets and erythrocytes and to relate these concentrations to biomarkers of iron status. MethodsA total of 138 soccer players divided according to sex: men (n = 68) and women (n = 70) participated in the present study. All participants resided in the city of Cáceres (Spain). Erythrocyte, haemoglobin, platelet, plateletcrit, ferritin and serum iron values were determined. Cadmium and lead concentrations were quantified by inductively coupled plasma mass spectrometry. ResultsThe women had lower haemoglobin, erythrocyte, ferritin and serum iron values (p < 0.01). Regarding cadmium, the women showed higher concentrations in plasma, erythrocytes and platelets (p < 0.05). As for lead, they also showed higher concentrations in plasma, relative values of erythrocytes and relative values of platelets (p < 0.05). Significant correlations were observed between cadmium and lead concentrations with biomarkers of iron status. ConclusionsCadmium and lead concentrations are different between sexes. Biological differences between sexes and iron status could influence cadmium and lead concentrations. Lower serum iron concentrations and markers of Fe status increase Cd and Pb concentrations. Ferritin and serum iron have been directly related to increased Cd and Pb excretion.

Effect of B2O3 on viscosity of high-magnesia blast furnace slag

Metallurgical companies in the Urals account for 50 – 60 % of local raw materials. Its deficit is compensated by the use of materials imported from Central Russia, the Kola Peninsula and Kazakhstan. Replacing them with the local raw materials would increase the competitiveness of metal produced in the Urals, so the question of assessing the possibility of replacing imported raw materials with local ones is very relevant. Such raw materials could be siderite ores from the Bakal deposit. They are not in demand by metallurgists because of their low iron content and high magnesium content. With growth of siderites in a charge the magnesium oxide content in slag increases that influences its viscosity and makes it difficult or impossible to smelt using more than 20 % of siderites. The use of boron oxide has been suggested to liquefy the slag. The synthetic slag containing 26.8 % CaO, 38.1 % SiO2 , 11.8 % Al2O3 , 23.6 % MgO, simulating composition of slag from MMK blast-furnace smelting with the addition of 30 % of burnt siderites is short and unstable. The temperature corresponding to the slag viscosity at the blast furnace outlet (0.5 Pa·s) is 1390 °C and the temperature corresponding to the melting point (viscosity 2.5 Pa·s) is 1367 °C. If boric anhydride is added to such a slag, it becomes long and stable. In the melts, when the proportion of B2O3 is increased from 0 to 12 %, the temperature at which the slag viscosity is 0.5 Pa·s and 2.5 Pa·s decreases to 1260 °C, and 1100 °C, respectively. This makes it possible to significantly increase the siderite content in blast furnace charge.

Higher concentrations of serum transferrin receptor in children than in adults

The serum transferrin receptor (TfR) concentration in adults is suggested to provide a sensitive measure of iron depletion and together with the serum ferritin concentration to indicate the entire range of iron status, from iron deficiency to iron overload. However, little is known about TfR concentrations in children. Our objective was to compare serum TfR and ferritin concentrations and their ratios in children and adults and look for correlations between TfR concentrations and other measures of iron status. Our study groups were healthy 1-y-old infants (n = 36), 11-12-y-old prepubertal boys (n = 35), and 20-39-y-old men (n = 40). TfR concentrations were higher in infants (x; 95% reference interval: 7.8 mg/L; 4.5, 11.1) than in prepubertal boys (7.0 mg/L; 4.7, 9.2) and higher in prepubertal boys than in men (5.8 mg/L; 3.1, 8.5). Geometric mean TfR-ferritin ratios were higher in infants (316; 95% reference interval: 94, 1059) than in prepubertal boys (219; 78, 614) and higher in prepubertal boys than in men (72; 23, 223). By multiple linear regression analysis, the best predictors of TfR concentration were serum iron (P = 0.004) and log serum ferritin (P < 0.0001), both being inverse correlations (R2 = 0.32). Mean corpuscular volume, blood hemoglobin, transferrin iron saturation, transferrin, and even age seemed to not have an influence on the TfR concentration and erythropoiesis was not a determinant of TfR concentration. Low serum ferritin and iron concentrations, even within the normal physiologic range, result in high TfR concentrations. The lower the iron stores, the stronger the influence of ferritin on TfR. A high TfR concentration in children, especially in infants, is a response to physiologically low iron stores. Age-specific reference concentrations for TfR are needed.

Enhancement of soil fertility and yield of Capsicum frutescens (Green chilli) through application of bagasse Ash in soil

A pot experiment was conducted during 2022-23 at the research area of the Department of Environmental Science, Bareilly College, Bareilly to evaluate the effect of bagasse ash on growth, yield and quality of Capsicum frutescens (Green chilli) and also on soil fertility sugarcane. To achieve the current research work , sugar industry bagasse ash was applied to capsicum frutescens crops in pots having 1 kg soil @ 20% , 40%, 60%, 80% , 100,% respectively . When we compare the control sample. The physicochemical properties of soil under the investigation was having a pH (7.6), low in organic matter (8300 mg kg-1), and low content of Nitrogen (337 mg kg-1), Phosphorus (4.0 mg kg-1), Zinc(5.7 mg kg-1) and Iron (5.2 mg kg-1) . Bagasse ash was a rich source of micronutrients like Fe, Mn, Zn and Cu and also contained sufficient amounts of Potassium and Phosphorus. Consequently, total porosity of soil, presence P, K, Fe, Mn, Zn and Cu content in soil, increased with the levels of bagasse ash application. On the other hand, dry bulk density declined which shows a positive effect on plant growth. ECe and pH of the soil was minutely increased. After the application of bagasse ash in pots yields of capsicum frutescens crop also enhanced. It is recommended that application of 40-60% bagasse ash will result in enhanced yield of capsicum frutescens.

Dietary Habits and Nutrient Deficiencies in a Cohort of European Crohn's Disease Adult Patients.

Wrong dietary habits, such as the Western-style diet, are considered important risk factors for the development of Inflammatory Bowel Diseases (IBDs). Nevertheless, the role of dietary patterns in the clinical management of IBD patients has not been fully investigated yet. Fifty-four patients diagnosed with active Crohn's disease (CD) were enrolled and subjected to nutritional intake analysis through a weekly food diary. Nutritional patterns were analyzed, and nutrient intake was compared with those of 30 healthy subjects (HS). Blood levels of cholesterol, folic acid, minerals (K, Mg, Fe) and amino acids, were measured in CD patients to assess the presence of nutritional deficiencies. CD patients, with respect to HS, consumed significantly lower amounts of fiber, vitamins (A, E, C, B6, folic acid) and β-carotene. Their calcium, potassium, phosphorus, iron, magnesium, copper and iodine intake were also found to be significantly lower. In blood, CD patients had significantly lower concentrations of total cholesterol, potassium, iron, and amino acids. Active CD patient diet was significantly different from those of HS and may contribute to the establishment of nutritional deficiencies. Intestinal malabsorption was evidenced in these patients. Correction of the diet with specific nutritional plans is a necessary therapeutic step for these patients. ClinicalTrials.gov: NCT02580864.

'Green-to-Green': Iron oxides embedded in lignin-based carbon scaffolds for water remediation via oxidation excluding free-radical pathways.

Advanced oxidation processes (AOP) are a common tool to remove organic compounds from the water cycle. The process is mostly relied on free radicals (i.e., SO4•- and HO•) with high oxidation power in solution. Surface-mediated mechanism could improve this process to prevent undesired quenching of aqueous radicals that widely exists in free radical pathways and alleviate metal leaching through direct electron transfer. In this work, a facile low-temperature pre-treatment combined with pyrolytic strategy was employed to construct a green catalyst with iron oxides embedded in Kraft-lignin derived bio-char (γ-Fe2O3 @KC), upon which radicals stay surface mediated and the activity-stability trade-off is achieved for pollutant degradation. The γ-Fe2O3 @KC is capable of activating PMS to generate non-radical species which are more stable (1O2 and Fe(V)=O) and of enhancing electron transfer efficiency. A surface-bound reactive complex (Catalyst-PMS*) was identified by electrochemical characterization and was discussed with primary surface-bound radical pairs to explain the contradictions between quenching and EPR detection results. We analyzed the γ-Fe2O3 @KC as a PMS-activating catalyst for a wider range of oxidation targets, such as Rhodamine B (∼100%), p-nitrophenol (∼85%), and Ciprofloxacin (∼63%), and found competitive removal efficiencies. The system also shows an encouraging reusability for at least 5 times and high stability at pH 3-9, and the low concentration of iron in γ-Fe2O3 @KC/PMS system implies the carbon scaffold of biochar alleviate the leakage process. The combined findings highlight the applicability in 'green (source) to green (application)' processes using cost-effective and bio-friendly iron@carbon catalysts, where alternative oxidation pathways are activated to play a dominant role for water purification.

Mineralogical Study of Bauxite of Kenco Area, Landak District, West Kalimantan Province, Indonesia

Indonesia is a country with a tropical climate that allows for high levels of weathering. Bauxite is the result of weathering rocks that have high aluminum content, low iron content, and little quartz content. The formation of bauxite deposits is controlled by source rock which is rich in Al element, tropical climatic conditions, and geomorphological conditions that allow the formation of the accumulation of weathered source rock products. The altered silicate minerals due to weathering result in the silica element being released from the crystal bonds and some iron are released so that the aluminum element is concentrated as a residual precipitate. X-ray diffraction (XRD) analysis on 16 bauxite samples which are estimated to represent the overburden horizon, bauxite ore horizon, clay horizon, and source rock to establish the mineral composition of bauxite. Mineral groups in the overburden horizon, bauxite ore horizon, and clay horizon are alumina, iron, titanium, silicates, carbonates, sulfides, and sulfates, while mineral groups in source rock are iron, titanium, silicate, sulfide, and sulfate. The type of bauxite in the study area is gibbsite bauxite based on the dominant appearance frequency of gibbsite compared to mineral corundum as an alumina group.

Granitic‐melt and carbonic‐fluid inclusions in diopside megacrysts from ankaramitic basalt dikes at Kamisano, Yamanashi prefecture, northeastern Japan

AbstractLarge phenocrysts, known as megacrysts, are focal points for research due to their ability to encapsulate large inclusions suitable for precise chemical analyses. Ankaramite, a distinctive type of undifferentiated volcanic rock, stands out due to its high MgO and CaO contents and the presence of abundant Ca‐rich clinopyroxene (diopside) and less common Mg‐rich olivine phenocrysts. In this study, granitic melt inclusions together with carbonic fluid inclusions were identified within diopside megacrysts of ankaramitic basalt dikes in the Kamisano region, Yamanashi Prefecture, Japan. The identified melt inclusions are completely crystallized and primarily composed of quartz, alkali feldspar, and plagioclase, with smaller amounts of pargasite, augite, apatite, and sulfides. Small amounts of residual glass were also occasionally observed in the inclusions. The average chemical composition of these granitic melts within the inclusions corresponds to that of calc‐alkaline granodiorite and the melts are characterized by low water content (0.38 wt%) and high concentrations of sulfur (7000 ppm), copper, and iron. The findings suggested that the composition of granitic melt inclusions may provide insights into the characteristics of near‐surface hydrothermal metal ore deposits. The diopside megacrysts also contain CO2H2O fluid inclusions, which are completely crystallized and mainly comprised of calcite and chlorite, along with small amounts of quartz. The crystals are interpreted to have formed by the reaction of original CO2H2O fluids and host diopside. The diopside megacrysts are estimated to have started crystallization from tholeiitic basalt at a depth of ~30 km in the lower crust, and trapped fluids and granitic melts as inclusions at a shallower depth when the tholeiitic magma ascended.

CHEMICAL COMPOSITION OF TAILINGS ENRICHMENT OF MAGNETITE QUARTZITES OF THE KRYVYI RIH BASIN

The major and minor element compositions of the tailings at the Kryvyi Rih processing plants (i.e., Inguletsky, ArcelorMittal Kryvyi Rih, and Central) were studied. A good relationship between the composition of the tailings and the mined ore, which was to be enriched, was confirmed. The main trends in the techno geochemical changes in the process of enrichment were determined. Differences were measured of the tailings composition between various processing plants of the Kryvyi Rih basin. That is, the tailings from the Ingulets plant are more ferruginous with an iron content of 23.7 wt % and are almost twice as high compared to those of the Central and ArcelorMittal Kryvyi Rih plants. Tailings from ArcelorMittal Kryvyi Rih are more carbonaceous and aluminous and have low iron and silicon contents. Tailings of the Central plant are more siliceous and have minimum of alumina and carbonates and have the average iron content. In terms of the major elements, the tailings are generally enriched in silicon, aluminum, manganese, magnesium, calcium, sodium, potassium, phosphorus, sulfur, and depleted in iron and titanium, compared to the original ore. In terms of minor elements, the tailings are generally enriched in the some lithophile (including rare earth) elements Sr, Y, Sc, Li, and partially Zr, and depleted in elements that are concentrated in magnetite, Ni, Th, U, and Ge, compared to the original ore. The chalcophile elements Cu, Pb, Zn, Ag are characterized by an inhomogeneous and variable distribution. The most significant among them is Zn, which can have significant concentrations (up to 230 g/t in the tailings). These results can be used to determine the directions of tailing using and to assess the impact of tailings on the environment.

Defect pairing in Fe-doped SnS van der Waals crystals: a photoemission and scanning tunneling microscopy study.

We investigate the effect of low concentrations of iron on the physical properties of SnS van der Waals crystals grown from the melt. By means of scanning tunneling microscopy (STM) and photoemission spectroscopy we study Fe-induced defects and observe an electron doping effect in the band structure of the native p-type SnS semiconductor. Atomically resolved and bias dependent STM data of characteristic defects are compared to ab initio density functional theory simulations of vacancy (VS and VSn), Fe substitutional (FeSn), and Fe interstitial (Feint) defects. While native SnS is dominated by acceptor-like VSn vacancies, our results show that Fe preferentially occupies donor-like interstitial Feint sites in close proximity to VSn defects along the high-symmetry c-axis of SnS. The formation of such well-defined coupled (VSn, Feint) defect pairs leads to local compensation of the acceptor-like character of VSn, which is in line with a reduction of p-type carrier concentrations observed in our Hall transport measurements.

Предварительные результаты технико-технологического анализа керамики с поселения Потаповы лужки-III (Томское Приобье)

The article presents the results of a technical and technological analysis of the developed and late Bronze Age ceramics from the Potapovy Luzhki-III settlement in the Tomsk Ob river region. The studies were carried out within the framework of the historical and cultural approach according to A.A. Bobrinsky’s method. The main task was to identify the specific features of cultural traditions in the selection of raw materials and the preparation of the pottery paste, and a comparative analysis of the data obtained. As a result of the study, it was established that iron-rich and non-iron non-sanded and heavily sanded clays were used for the making of ceramics. The Samus ceramics are made mainly from plastic clays differing in their degree of iron content, and the vessels of the late Bronze Age are made from low iron content clays with high content of fine sand. A single recipe was revealed: clay + crushed stone + organic matter. A comparative analysis with previously obtained data showed that the discovered tradition to use low iron content clays and non-iron clays for the ancient ceramics of the Tomsk Ob river region is also characteristic of the Bronze Age ceramics from the Potapovy Luzhki-III settlement. Also characteristic of this area is the addition of crushed stone to the pottery paste. It is noteworthy that there are no signs of mixing of cultural traditions in the preparation of the pottery paste on the site.

Determination of vitamin D, iron and n-3 fatty acids in adolescents with different eating habits.

Proper eating habits ensure human health, so it is important to eat a balanced diet and learn the basics of proper eating from an early age. Adolescence is considered very important period for maintaining good health in terms of nutrition. In the study, we monitored the eating habits of 182 adolescents aged 14-19 years with different eating habits (73 vegetarians and 109 nonvegetarians) using a questionnaire on nutrition and determination of selected blood parameters - vitamin D, iron and n-3fatty acids. Insufficient levels of vitamin D were determined in the whole group of adolescents, regardless of eating habits. Low iron concentrations negatively affect the biosynthesis of long-chain n-3 fatty acids, which was also reflected in our adolescents with alternative diets. Based on the obtained results, it is necessary to place emphasis on the composition of the diet in adolescent age.

Synthesis of Mesoporous Silica Incorporated with Low Iron Concentration and Gelatin Co-Template via The Ultrasonication Method and Its Methylene Blue Photodegradation Performance

In this work, low iron concentration incorporated on mesoporous silica with gelatin co-template (Fe2O3/GSBA-15) has been successfully synthesized via the ultrasonication method. The physical, chemical, and structural properties of the samples were investigated with X-Ray Diffraction (XRD), Scanning Electron Microscope- Energy Dispersive X-Ray (SEM-EDX), Fourier Transform Infra-Red (FTIR), and N2 adsorption-desorption. Results showed good distribution of low concentration of iron oxide on the gelatin mesoporous silica GSBA-15. Elemental and surface analysis presented that iron oxide incorporation with higher concentration exhibited lower surface area due to the blocking pore. The highest photocatalytic activity on the methylene blue dye degradation was achieved at 10% Fe2O3/GSBA-15 with ~80% efficiency. The results revealed that the photocatalytic activity of Fe2O3/GSBA-15 enhanced with the presence of iron oxide. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Ancient metalworking at Yodhawewa site, Sri Lanka: tracing the archaeological and geochemical relationship by analyzing soil and slags

The Yodhawewa archaeometallurgical site was the latest discovery in Sri Lanka in 2018. This study aimed to trace the archaeological and geochemical relationship by analyzing the soil and slags of the site dating back to the c. first to eighth centuries AD. The analysis was mainly based on the X-ray fluorescence (XRF) method. The soil chemistry resulted in some clues to special metal processing zones in the excavation-1 area. The cultural layers of that area (profiles 1 and 2) showed relatively high copper composition (max. 470 ppm), and crucible fragments containing copper particles were also detected in the same layers. The vertical distribution of soil elements and their correlations with TiO2 suggested that long-term metal activity may have affected changes in environmental soil chemistry. Relatively high phosphorus was indicated in the soil-related furnace wall, suggesting the artificial addition of organic matter to the clay body during the furnace wall construction to withstand the high temperatures. High iron slag (HIS) varies from 12.96 to 49.63 wt% of Fe2O3 and shows high MnO, P2O5, and V. Lightweight amorphous/glassy slags (LIS) associated with secondary refining have low iron content and a high CaO and Sr composition.

High-precision abundances of first-population stars in NGC 2808: confirmation of a metallicity spread

Photometric investigations have revealed that Galactic globular clusters (GCs) exhibit internal metallicity variations amongst the so-called first-population stars, which until now were considered to have a homogeneous initial chemical composition. This is not fully supported by the sparse spectroscopic evidence, which so far gives conflicting results. Here, we present a high-resolution re-analysis of five stars in the Galactic GC NGC 2808 taken from the literature. Target stars are bright red giants with nearly identical atmospheric parameters belonging to the first population according to their identification in the chromosome map of the cluster, and we measured precise differential abundances for Fe, Si, Ca, Ti, and Ni to the ∼0.03 dex level. Thanks to the very small uncertainties associated with the differential atmospheric parameters and abundance measurements, we find that target stars span a range of iron abundance equal to 0.25 ± 0.06 dex. The individual elemental abundances are highly correlated with the positions of the stars along the extended sequence described by first-population objects in the cluster chromosome map: bluer stars have a lower iron content. This agrees with inferences from the photometric analysis. The differential abundances of all other elements also show statistically significant ranges that point to intrinsic abundance spreads. The Si, Ca, Ti, and Ni variations are highly correlated with iron variations and the total abundance spreads for all elements are consistent within the error bars. This suggests a scenario in which short-lived massive stars exploding as supernovae contributed to the self-enrichment of the gas in the natal cloud while star formation was still ongoing.

Iron-rich sand promoted nitrate reduction in a study for testing of lignite based new slow-release fertilisers

The N losses and agronomic performances of newly developed slow-releasing fertilisers (SRFs; Epox5 and Poly5) were tested against conventional N fertilisers, urea and diammonium phosphate (DAP), in a climate-controlled lysimeter system. The dry matter (DM) yield and N losses of SRFs were not significantly different from urea and DAP. However, nitrate leaching and nitrous oxide (N2O) losses were unexpectedly low and therefore, it was inferred that nitrate underwent a chemical transformation. It was observed that a thick fibreglass wick interrupted drainage and created an anaerobic condition in the soil. The subsoil was found to have a high extractable total iron and it was postulated that iron played a role in the observed low level of N losses. An investigation was carried out with a factorial design using sand types and rates of N application as the main factors. Two types of sand; with high and low iron concentration and four levels of N applications; 0 (control), 50, 100 and 200 kg N ha−1 were employed in a leaching column and nitrate and N2O losses were measured. The nitrate leaching was significantly (P < 0.05) affected by sand types wherein a lower nitrate level was recorded for high‑iron concentration sand than for low-iron concentration sand at all N application levels. The N2O emission was significantly (P < 0.05) lower for high-iron sand than for low-iron sand for the 200 N treatment, but not significantly different between sand types for other treatments. These observations provide evidence for the involvement of iron in nitrate transformation under anaerobic conditions and it was hypothesised path was dissimilar nitrate reduction (DNR). Further studies are recommended, to identify the underlying mechanism responsible for nitrate reduction with iron-rich sand.