Soluble Iron Research Articles

Melatonin promotes iron uptake and accumulation in peach

• Melatonin promoted growth of peach. • Melatonin increased iron content in peach. • Melatonin increased chemical form of iron content that can be absorbed by plants. Iron deficiency leads to stunted growth in fruit trees and reduces the yield and quality of fruits. To increase the uptake of iron in fruit trees and provide a reference to control iron deficiency, the effects of different concentrations of melatonin (MT) on iron uptake in peach ( Prunus persica ) were studied by a pot experiment. Concentrations of 0, 50, 100, 150, and 200 µM MT were used in this experiment. MT increased the biomass of peach. Concentrations of 100, 150, and 200 µM MT increased the contents of total and active iron in peach. Concentration of 150 µM MT got the maxmiums of total iron contents in stems and leaves, which increased by 28.79% and 36.11%, respectively, compared with the control. Correspondingly, concentrations of 100 and 150 µM MT upregulated the genes related to iron absorption, including the ferric reduction oxidase 7 ( FRO7 ), vacuolar iron transporter 1 ( VIT1 ), and ferric reduction oxidase 4 ( FRO4 ), while downregulating the vacuole genes vacuolar iron transporter homolog 4 ( VITH4 ) and natural resistance-associated macrophage protein 3 ( NRAMP3 ) that are related to vacuolar iron transport. The concentrations of absorbable iron forms, including the water soluble iron, adsorbed iron, carbonate and strongly adsorbed iron, and manganese oxide bound iron, in the soil increased, and the soil pH value decreased following the addition of 100, 150, and 200 µM MT. A correlation analysis showed that the contents of total and active iron in peach correlated with the biomass, soil pH value, absorbable soil iron forms, and level of expression of the iron absorption related genes. These observations indicate that treated with 100–200 µM MT could promote the iron uptake and accumulation in peach by regulating the physiological metabolism related to iron.

THE INFLUENCE OF THE ANODE MATERIAL ON THE COURSE OF COMBINED PROCESSES DURING THE REGENERATION OF SULPHATE-ACID SOLUTIONS

The existing methods of regeneration of sulfo-acidic solutions, which contain iron sulfate, formed after technological operations for the preparation and etching of metal parts at metalworking enterprises are not effective and therefore are not used at Ukrainian enterprises. They are either aimed at sedimentation of the sludge of sparingly soluble iron compounds after neutralization of unreacted sulfuric acid or at dilution of the formed spent sulfo-acid solutions. The electrochemical method of regeneration of such spent sulfo-acid solutions is not properly researched. A feature of the development of technology and equipment for regeneration is a decrease in the content of iron ions and an increase in the concentration of sulfuric acid during the regeneration process. The process of electrochemical regeneration of spent steel etching solutions is characterized by a significant change in the composition of the etching solution and the temperature of the etching process. At the beginning of work, the initial solution of sulfuric acid reaches a concentration of 2.0 mol·dm-3 and does not contain iron (II) sulfate. In the process of digestion, the concentration of sulfuric acid decreases to 0.5 mol·dm-3, and the concentration of iron (II) sulfate increases accordingly. Therefore, the course of the anodic process was studied for the following solution compositions: 0.5 mol·dm-3; 1.0 mol·dm-3 and 1.5 mol·dm-3 H2SO4. Under the conditions of a decrease in the concentration of sulfuric acid, its chemical activity also decreases when interacting with iron oxides and hydroxides. An increase in the temperature of the entire process is used to increase the reactivity of the pickling solutions. The main process at the platinum anode is the release of oxygen in a wide range of current densities and a significant overvoltage of the entire process. Taking into account the obtained voltage-voltage dependences, it can be seen that the current rises when reaching potentials that significantly exceed the standard potential for obtaining oxygen from water. The advantage of the platinum anode is the slight influence of the concentration of sulfuric acid on the kinetics of the anode process. The obtained results were used for comparison with other alternative anode materials. Manganese dioxide was obtained by the method of pyrolysis of a coating solution of manganese monoacid applied to a titanium current lead, which can be represented by reaction (5) of the decomposition of manganese nitrate on a titanium plate. Due to the developed surface, the real current density was more than an order of magnitude lower on the TDMA than on the platinum anode with the same geometric dimensions. A lower current density contributed to a decrease in the steady-state potentials of oxygen release. The current density can be increased by an order of magnitude if surfactants are added to the working solution. A comparison of voltage-voltage dependences on platinum and TDMA indicates that the use of TDMA gives a more significant gain in energy consumption during the regeneration process. Taking into account that the range of current densities of 4-5 A/dm2 was determined for the cathode process according to the research results, the difference in the reduced polarization of the anode on TDMA, compared to platinum, is more than 400 mV, which will significantly reduce costs during unit operation. The use of TDMA is expedient in the galvanostatic mode of operation of the electrode unit for the process of electrochemical regeneration of spent sulfo-acid solutions of steel pickling.

Uptake mechanism of iron-phytosiderophore from the soil based on the structure of yellow stripe transporter

Calcareous soils cover one-third of all land and cause severe growth defects in plants due to the poor water solubility of iron at high pH. Poaceae species use a unique chelation strategy, whereby plants secrete a high-affinity metal chelator, known as phytosiderophores (mugineic acids), and reabsorb the iron-phytosiderophore complex by the yellow stripe 1/yellow stripe 1-like (YS1/YSL) transporter for efficient uptake of iron from the soil. Here, we present three cryo-electron microscopy structures of barley YS1 (HvYS1) in the apo state, in complex with an iron-phytosiderophore complex, Fe(III)-deoxymugineic acid (Fe(III)–DMA), and in complex with the iron-bound synthetic DMA analog (Fe(III)–PDMA). The structures reveal a homodimeric assembly mediated through an anti-parallel β-sheet interaction with cholesterol hemisuccinate. Each protomer adopts an outward open conformation, and Fe(III)–DMA is bound near the extracellular space in the central cavity. Fe(III)–PDMA occupies the same binding site as Fe(III)–DMA, demonstrating that PDMA can function as a potent fertilizer in an essentially identical manner to DMA. Our results provide a structural framework for iron-phytosiderophore recognition and transport by YS1/YSL transporters, which will enable the rational design of new, high-potency fertilizers.

Systematic changes in circumpolar dust transport to the Subantarctic Pacific Ocean over the last two glacial cycles

The input of the soluble micronutrients iron (Fe) and/or manganese (Mn) by mineral dust stimulates net primary productivity in the Fe/Mn-deficient Southern Ocean. This mechanism is thought to increase carbon export, thus reducing atmospheric CO2 during the Pleistocene glacial cycles. Yet, relatively little is known about changes in the sources and transport pathways of Southern Hemisphere dust over glacial cycles. Here, we use the geochemical fingerprint of the dust fraction in marine sediments and multiisotope mixture modeling to identify changes in dust transport to the South Pacific Subantarctic Zone (SAZ). Our data show that dust from South America dominated the South Pacific SAZ during most of the last 260,000 a with maximum contributions of up to ∼70% in the early part of the glacial cycles. The enhanced dust-Fe fluxes of the latter parts of the glacial cycles show increased contributions from Australia and New Zealand, but South American dust remains the dominant component. The systematic changes in dust provenance correspond with grain size variations, consistent with the circumpolar transport of dust by the westerly winds. Maximum contributions of dust from more proximal sources in Australia and New Zealand (up to ∼63%) paired with a finer dust grain size indicate reduced westerly wind speeds over the South Pacific SAZ during deglacial and peak interglacial intervals. These quantitative dust provenance changes provide source-specific dust-Fe fluxes in the South Pacific SAZ and show how their systematic changes in magnitude and timing influence the Southern Ocean dust-Fe feedback on glacial-interglacial to millennial time scales.

Insights into the roles of aerosol soluble iron in secondary aerosol formation

Aerosol soluble iron (Fe) is crucial in the biogeochemical cycle and atmospheric processing. In this study, soluble Fe and their solubility in fine particles (PM2.5) were investigated over Xi'an, China to insight the iron sources and the roles in aerosol formation. Our results showed that most Fe in PM2.5 was insoluble (Fe solubility: 25.5 ± 11.3%). Seasonal variations exhibited that the highest soluble Fe(II) showed in winter (308.9 ng m−3) and the highest Fe(III) levels were in summer (116.3 ng m−3). Source identification of soluble Fe illustrated that industrial coal combustion contributed most in summer, whereas mineral dust, biomass burning, and coal combustion dominated in spring, autumn, and winter, respectively. Moreover, strong correlations between soluble Fe and water-soluble inorganic ions suggested soluble Fe is related to not only primary sources but also secondary formations. Furthermore, a negative correlation (R = −0.56) was observed in winter between Fe(III) and SO42−, indicating that the oxidation pathway of Fe(III) catalysis should play a vital role in sulfate formation in winter. In addition, secondary brown carbon presented positive correlations with soluble Fe(II), while negatively correlated with soluble Fe(III), potentially suggested an important pathway for the formation of secondary BrC. Our study provides a broader understanding of Fe solubility and their roles in atmospheric chemical processing.

Pengaruh Pemberian Zeolit Alam Teraktivasi terhadap Sifat Kimia Tanah Podsolik

Podsolic soil in South Kalimantan has a low fertility rate including pH, organic matter, cation exchange capacity (CEC), solubility P, and has a high solubility of aluminum (Al) and iron (Fe). It causes fixation P by Al and Fe in the form of Al-P and Fe-P, which makes P difficult to dissolve in the soil. Zeolite is an ameliorant that is capable of improving soil chemical properties based on its ability to carry out ion exchange, adsorption, absorb molecules, increase fertilizer efficiency, increase soil CEC, and the availability of Ca, K, and P ions, which can reduce aluminum content. The purpose of this study was to identify the pattern of relationships caused by application of activated natural zeolite on Podsolic soil against pH, CEC, available P, soluble Fe, and exchangeable Al. This study was a pot experiment weighing 0.5 kg of soil, carried out in a greenhouse and arranged using CRD a single factor . The incubation period was carried out for eight weeks with three replications. The results showed that there was a relationship between the zeolite dose activated against the available P (the linear regression equation Y = 0.6 + 0.032 X, R2 = 0.4969, and r = 0.7006*), while the doses of zeolite had no significant effect on pH, CEC, soluble Fe, and exchangeable Al.

Electrogenerated iron-based adsorbents: A case study of an azo dye removal viewed from a fundamental physico-chemical perspective

The aim of this manuscript was to investigate the electrogeneration of iron-based solids and their use in the adsorption of an azo dye. Experiments of electrochemical generation of iron hydr(oxides) were carried out in a Hoffman cell and in a well-stirred batch reactor at 25 °C. The oxidation of iron metal at the anode and the reduction of water at the cathode were the electrochemical reactions confirmed to occur. A 22 factorial design of experiments was applied to investigate the effect of initial pH and current on the current efficiency for the production of ferrous ion at an electrolyte concentration of 300 g L−1. The current efficiency for Fe2+ was much lower than unity (0.204 ± 0.009) and it was statistically independent of the examined factors (p > 0.05). An approximately 3:1 M mixture of amorphous ferric and ferrous hydroxides was electrogenerated before being possibly converted to dehydrated hydroxides such as magnetite. The iron hydroxides were formed by precipitation reactions of soluble iron species at a rate constant higher than 0.072 ± 0.013 s−1. Additional experiments of electrogeneration of these solid adsorbents at electrolyte concentrations between 250 and 1.5 g L−1 revealed a significant (p ≤ 0.05) decrease in the current efficiency for Fe2+ formation from 0.180 ± 0.006 to 0.118 ± 0.008. Experiments of tartrazine adsorption on the electrogenerated iron oxyhydroxides were carried out batchwise at different initial concentrations of the dye at 25 °C. Electrogeneration of oxyhydroxides and adsorption were described correctly by detailed kinetic models. The crystallinity of the electrogenerated adsorbent was examined by X-ray diffraction analysis, while its specific surface area, pore volume and average pore size were from BET analysis. SEM and EDX analyses were conducted to examine its morphology and elemental composition.

Reductive biomining of pyrite by methanogens.

Pyrite (FeS2) is the most abundant iron sulfide mineral in Earth's crust. Until recently, FeS2 has been considered a sink for iron (Fe) and sulfur (S) at low temperature in the absence of oxygen or oxidative weathering, making these elements unavailable to biology. However, anaerobic methanogens can transfer electrons extracellularly to reduce FeS2 via direct contact with the mineral. Reduction of FeS2 occurs through a multistep process that generates aqueous sulfide (HS-) and FeS2-associated pyrrhotite (Fe1-xS). Subsequent dissolution of Fe1-xS provides Fe(II)(aq), but not HS-, that rapidly complexes with HS-(aq) generated from FeS2 reduction to form soluble iron sulfur clusters [nFeS(aq)]. Cells assimilate nFeS(aq) to meet Fe/S nutritional demands by mobilizing and hyperaccumulating Fe and S from FeS2. As such, reductive dissolution of FeS2 by methanogens has important implications for element cycling in anoxic habitats, both today and in the geologic past.

Aerosol Iron Solubility Specification in the Global Marine Atmosphere with Machine Learning.

Aerosol iron (Fe) solubility is a key factor for the assessment of atmospheric nutrients input to the ocean but poorly specified in models because the mechanism of determining the solubility is unclear. We develop a deep learning model to project the solubility based on the data that we observed in a coastal city of China. The model has five variables: the size range of particles, relative humidity, and the ratios of sulfate, nitrate and oxalate to total Fe (TFe) contents in aerosol particles. Results show excellent statistical agreements with the solubility in the literature over most worldwide seas and margin areas with the Pearson correlation coefficients (r) as large as 0.73-0.97. The exception is the Atlantic Ocean, where good agreement is obtained with the model trained using local data (r: 0.34-0.66). The model further uncovers that the ratio of oxalate/TFe is the most important variable influencing the solubility. These results indicate the feasibility of treating the solubility as a function of the six factors in deep learning models with careful training and validation. Our model and projected solubility provide innovative options for better quantification of air-to-sea input of aerosol soluble Fe in observational and model studies in the global marine atmosphere.

Functional iron status of chronic kidney disease patients at the University of Ilorin Teaching Hospital, Ilorin, Nigeria.

Functional iron deficiency has been found to be a common cause of poor response to erythropoiesis stimulating agents in anaemic patients with chronic kidney disease (CKD). Assess the functional iron status of patients with chronic kidney disease. This was a hospital based cross sectional study. The study subjects were chronic kidney disease patients with age and sex matched healthy controls. Full blood count, serum ferritin, soluble transferring receptor, C-reactive protein, serum iron and total iron binding capacity were measured in the patients and healthy controls.Data was analyzed with statistical package for the social sciences software version 22.0. And the level of statistical significance was set at p. value < 0.05. The mean ± SD of the age of patient with CKD was 55.0 + 15.4 years, while that of controls was 52.7 + 13.6 years. The mean serum ferritin, serum iron, TIBC and CRP were significantly higher in patients compared with controls (p<0.001, 0.023, <0.001 and 0.001) respectively. Functional iron deficiency was seen in 19.5% of patients with CKD. The predominant form of iron deficiency in our study was functional iron deficiency.

Earthworms affect reactive surface area and thereby phosphate solubility in iron-(hydr)oxide dominated soils

Sustainability of agricultural systems is at stake, as phosphorus (P) is a non-renewable resource while its global reserves are limited. Stimulating earthworm activity can be a technology to increase the level of readily plant-available phosphate (PO4). However, conclusive evidence on the mechanisms underlying an earthworm-enhanced PO4 solubility is yet missing. This study aimed to reveal possibly overlooked pathways by which earthworms affect PO4 solubility, and quantify the relative importance of all contributing mechanisms. Therefore, we set up a greenhouse pot experiment in which we investigated the large increase in water-extractable PO4 in casts of three earthworm species (Lumbricus rubellus, Aporrectodea caliginosa, Lumbricus terrestris) in soils with either predominantly Fe- or Al-(hydr)oxides. Oxalate-extractable PO4 was increased in earthworm casts compared to bulk soil which can be attributed to the mineralisation of natural organic matter (NOM). Surface complexation modelling was used to elucidate the mechanisms that control earthworm-enhanced PO4 solubility. The results of our modelling showed that the increase in pH in earthworm casts relative to bulk soil affects PO4 solubility only to a minor extent. Besides NOM mineralisation, two major mechanisms contributing to earthworm-enhanced PO4 solubility are (i) a decrease in the reactive surface area (RSA) of the metal-(hydr)oxide fraction; and (ii) a decrease in the competition between NOM and PO4 for binding sites of the metal-(hydr)oxides. As the newly discovered decrease of the RSA was only found for Fe-(hydr)oxide-dominated soils, earthworms have the largest potential to enhance PO4 solubility in those soils.

Efficiency and mechanism of zero-valent iron/nitrilotriacetic acid/peroxymonosulfate system for degrading sulfamethazine

In this paper, the efficiency and mechanism of using nitrilotriacetic acid(NTA) as a complexing agent to enhance the zero-valent iron(Fe0)/peroxymonosulfate(PMS) system to remove sulfamethazine(SMZ) from water are discussed. Research results show that the addition of NTA increases the soluble iron by 3.05 times, and the decomposition rate of PMS increases from 27% to 62%. Keeping other conditions unchanged and increasing the concentration of PMS to 0.2 mM, the degradation rate reaches the peak, continued increase of PMS concentration will decrease the degradation rate. The degradation rate of SMZ is positively correlated with Fe0 concentration. The effect of different inorganic ions on the degradation of SMZ was investigated. The high concentration of Cl− promoted the degradation effect, and the reaction rate constant of the system is increased by 1.67 times when the Cl− dosing is 10 mM. The PMS/Fe0/NTA system degrades SMZ up to 79.36% in actual water bodies. The degradation of SMZ is mainly by Smiles-type rearrangement, sulfonamide bond breaking, etc. The toxicity test proves that the inhibition rate of luminescent bacteria before and after degradation decreases from 61.86% to 40.47%, with an overall decreasing trend of toxicity.

Combining iron affinity-based fractionation with non-targeted LC-ESI-TOFMS for the study of iron-binding molecules in dissolved organic matter.

The low solubility of inorganic iron(III) in seawater leads to very limited availability of this important micronutrient for marine organisms. Estuarine or oceanic iron is almost entirely bound to organic ligands of mainly unknown chemical structure. In this context, riverine input of iron rich, land-derived dissolved organic matter (DOM) can play an important role in coastal areas and investigation of potential Fe-ligands in DOM is of high interest. Previous studies have suggested that iron is predominantly bound to the high molecular weight fraction of DOM, but distributed over the entire size range. Logically, structural elucidation needs to start from the smallest building blocks. A model study targeting low molecular weight iron-binding constituents in Suwannee River natural organic matter (NOM) using Fe-loaded Chelex or silica for immobilized-metal affinity (IMAC)-based fractionation was undertaken. The binding strengths of different compounds could be qualitatively assessed using a differential analysis workflow. IMAC-fractionated samples were acidified and analyzed via liquid chromatography high resolution mass spectrometry (LC-HRMS) and molecular formulas were assigned using state of the art software. A total of 144 Fe-binding constituents in Suwannee River NOM were found to be of interest with the largest number observed to interact with Chelex at pH 4 (55%), and the smallest with silica at neutral pH (24%). Most binding constituents were found in the lignin- and tannin-type region of the van Krevelen plot. Results from this study support the hypothesis that very low molecular weight constituents (below 300 Da) can play a role in the iron binding mechanism of DOM and demonstrate that the employed analytical workflow is suitable for their detection.

Influence of non-stationary electric current on dissolution оf metals in aqueous solutions of alkali

Non-stationary effects can be widely used as an intensifying factor in technological processes and as a tool for studying chemical systems. Studies of energy effects on structural transformations in liquid systems can make it possible to significantly intensify many chemical and metallurgical processes. We have studied the solubility of aluminum, iron and molybdenum in alkaline solutions under the influence of alternating electric current. A two-electrode cell was used. The electrodes were made from dissolved metal. The frequency of the electric current varied from 20 to 200,000 Hz. In the process of dissolving aluminum in an alkaline solution at the same current frequency and alkali concentration, the mass loss of the aluminum sample increases with increasing current strength up to 0.042-0.044 g. A further increase of current practically blocks the dissolution of aluminum - the change in mass was 0.005-0.007 g of Al. Increasing the alkali concentration to 5.7% KOH significantly reduces the dissolution of aluminum, the weight loss is 0.009 g. The entire surface of the electrodes is covered with a film after 6 hours of dissolution. An analysis of the phases on the aluminum surface showed that the film is a phase based on potassium. The thickness of the potassium film varies depending on the depth of immersion of the electrodes in the solution and on the time of the experiment. The structure and composition of potassium and aluminum compounds could not be established.

Relationship between thermal dehydroxylation and aluminium extraction from a low-grade kaolinite: Role of clay chemistry and crystallinity

The presented research investigates the impact of clay crystallinity and iron oxide content on thermal dehydroxylation of kaolinite and thus the impact on aluminium dissolution. Two clay samples with different crystallinity and purity levels (designated low-grade for the impurity rich and disordered kaolin, and high grade for the highly crystalline and relatively pure kaolin) underwent thermal treatment from ambient temperature to 850 °C in 50 °C increments, followed by acid digestion to recover aluminium. Infrared spectroscopy and X-ray diffraction were used to characterise the clays after thermal treatment and following acid digestion to gain insights into the chemistry of the process. Lower temperatures were required to achieve complete thermal dehydroxylation for the low-grade kaolin at 450 °C, in comparison to high-grade kaolin, which was complete at 650 °C. Solid-state 27Al Nuclear magnetic resonance (NMR) highlighted the emergence of Al(IV) at 600 °C and Al(V) at 650 °C, the latter of which corresponded to the complete thermal dehydroxylation of the kaolinite and was the main aluminium species responsible for aluminium dissolution. The iron oxide phases present within the low-grade kaolin resulted in phase transformation to insoluble aluminium spinels at lower temperatures (750 °C), which caused a reduction in the acid solubility of aluminium and iron. However, there were benefits associated with aluminium recovery from the low-grade kaolin, namely, less energy being required to achieve complete thermal dehydroxylation for aluminium dissolution. This finding holds significance for the utilisation of low-grade kaolin by industry, such as for production of new commodities such as high purity alumina.

DRY DATES POWDER INCORPORATED WITH VITAMIN C

Dates palm (Phoenix dactylifera L.) is an important crop which is cultivated in the warmer regions of the world. Semi-dry Aseel variety of dates is an important commercial variety of Pakistan which appears as yellow or golden colour. The iron content of aseel variety is 1.58±0.04 mg/100g. Vitamin C sources such as lemon peel and aonla powders used for formulating the product. Iron and Vitamin C combine to form an iron chelate complex which increases the solubility of iron. However, an excess of 200 mg of Vitamin C per 30 mg of elemental iron is required to enhance the absorption of highly available iron salts, such as ferrous sulphate. The aim of this study is to increase the bioavailability of iron in human metabolism. The drying characteristics of dry dates (TD, 60⁰C), lemon peel and aonla (TD, 60⁰C and HAO, 60⁰C) were observed. The proximate composition of the formulated samples were determined. The ascorbic acid content of the formulated samples T1 (58 mg/100 g), T2 (62.3 mg/100 g), T3 (450 mg/ 100 g) and T4 (468 mg/100 g) were found. Desired ranges of these quality parameters of the formulated samples were fixed and selected as the best product

Bio-accessibility of iron and copper from seven Kenyan anti-anaemia medicinal plants

Anaemia is a blood disorder which is widespread among populations of the world. In this study, seven medicinal plants used by one hundred and sixty herbalists from Nyamira County to manage anaemia were evaluated for iron and copper bio-accessibility. The competence of four hundred herbalists was assessed, of which 160 participated in the study. Twenty-one different medicinal plants were reported to be used by various herbalists to manage a number of ailments afflicting their communities in three sub-counties in Kenya. A total of ten different medicinal plants were found to be used by the herbalists to manage anemia which is endemic in the country. Seven of the medicinal plants, Aloe Vera, Carissa edulis, Croton macrostachyus, Clerodendrum myricoides, Melia azedrach, Toddalia asiatica and Warburgia ugandensis, were studied by all herbalists. The seven medicinal plants were prepared according to the herbalists&amp;#039; procedure and analyzed for iron and copper through flame atomic absorption spectrophotometer. The mean iron level in Carissa edulis from Borabu was the highest (2635.48 ± 17.33 mg/kg), while that in Warburgia ugandensis from the Nyamira study area was the lowest (175.76 ± 5.03 mg/kg). The highest mean copper level (9.2 ± 1.24 mg/kg) was reported in Melia azedrach from Ekerenyo, while the lowest (2.12 ± 0.02 mg/kg) was reported in Carissa edulis from the Nyamira study area. Fractionation results indicated that the proportion of iron potentially released (bio-accessible) from all the medicinal plants was quite small. Clerodendrum myricoides had the highest mean iron release and solubility (16.4 mg/kg), while Warburgia ugandensis had the lowest (5.94 mg/kg) among the medicinal plants. More iron and copper were extracted enzymatically as compared to the aqueous extraction. The amount of iron extracted in the intestinal mimicked phase was more than that extracted in the gastric phase, while the reverse was observed for copper. The levels of bio-accessible iron and copper from the medicinal plants, especially those released in enzymatic extraction are quite high and the plants can be used in the management of anaemia.

Role of Dust and Iron Solubility in Sulfate Formation during the Long-Range Transport in East Asia Evidenced by 17O-Excess Signatures.

Numerical models have been developed to elucidate air pollution caused by sulfate aerosols (SO42–). However, typical models generally underestimate SO42–, and oxidation processes have not been validated. This study improves the modeling of SO42– formation processes using the mass-independent oxygen isotopic composition [17O-excess; Δ17O(SO42–)], which reflects pathways from sulfur dioxide (SO2) to SO42–, at the background site in Japan throughout 2015. The standard setting in the Community Multiscale Air Quality (CMAQ) model captured SO42– concentration, whereas Δ17O(SO42–) was underestimated, suggesting that oxidation processes were not correctly represented. The dust inline calculation improved Δ17O(SO42–) because dust-derived increases in cloud-water pH promoted acidity-driven SO42– production, but Δ17O(SO42–) was still overestimated during winter as a result. Increasing solubilities of the transition-metal ions, such as iron, which are a highly uncertain modeling parameter, decreased the overestimated Δ17O(SO42–) in winter. Thus, dust and high metal solubility are essential factors for SO42– formation in the region downstream of China. It was estimated that the remaining mismatch of Δ17O(SO42–) between the observation and model can be explained by the proposed SO42– formation mechanisms in Chinese pollution. These accurately modeled SO42– formation mechanisms validated by Δ17O(SO42–) will contribute to emission regulation strategies required for better air quality and precise climate change predictions over East Asia.

Comparison of bioavailability and transporters gene expression of four iron fortificants added to infant cereals

Iron deficiency is one of the most important nutritional disorders around the world. To reduce this health problem in infants, most countries have developed different iron fortification programs as a long-term strategy. However, it is necessary to select the best iron source to get the highest bioavailability with the lowest impact on the organoleptic properties of the foods. The aim of this research was to assess the in vitro bioavailability and intestinal cellular transport of four iron sources (electrolytic iron: EI, ferrous fumarate: FF, a micronized and dispersible ferric pyrophosphate: MDFP, and ferrous sulphate heptahydrated: FSH) used to fortify infant cereals. Fortified cereals were in vitro digested and soluble fractions were then incubated in Caco-2 cells to study iron retention, transport and uptake. Moreover, mRNA expression of iron transporters and ferritin formation were also measured in cells incubated with the iron standard salts. Iron solubility, uptake percentage, transport and uptake efficiencies by the Caco-2 cells were significantly higher in cereals fortified with FSH than with EI, obtaining intermediate values for the other two iron fortificants. MDFP induced higher expression of iron transporters Zip-14 and HEPH than other iron sources. FSH promoted the highest iron storage protein ferritin, followed by FF and MDFP, while EI presented the lowest in vitro bioavailability due to its low solubility. This work demonstrated that iron absorption, storage, and gene expression of transporters depend on the source of iron. These are important challenges to be taken into consideration when assessing the potential of iron fortificants.

Mass fractions, solubility, speciation and isotopic compositions of iron in coal and municipal waste fly ash.

Deposition of anthropogenic aerosols may contribute significantly to dissolved Fe in the open ocean, affecting marine primary production and biogeochemical cycles; however, fractional solubility of Fe is not well understood for anthropogenic aerosols. This work investigated mass fractions, solubility, speciation and isotopic compositions of Fe in coal and municipal waste fly ash. Compared to desert dust (3.1 ± 1.1%), the average mass fraction of Fe was higher in coal fly ash (6.2 ± 2.7%) and lower in municipal waste fly ash (2.6 ± 0.4%), and the average Fe/Al ratios were rather similar for the three types of particles. Municipal waste fly ash showed highest Fe solubility (1.98 ± 0.43%) in acetate buffer (pH: 4.3), followed by desert dust (0.43 ± 0.30%) and coal fly ash (0.24 ± 0.28%), suggesting that not all the anthropogenic aerosols showed higher Fe solubility than desert dust. For the samples examined in our work, amorphous Fe appeared to be an important controlling factor for Fe solubility, which was not correlated with particle size or BET surface area. Compared to desert dust (-0.05‰ to 0.21‰), coal and municipal waste fly ash showed similar or even higher δ56Fe values for total Fe (range: 0.05‰ to 0.75‰), implying that the presence of coal or municipal waste fly ash may not be able to explain significantly smaller δ56Fe values reported for total Fe in ambient aerosols affected by anthropogenic sources.