Sulfate Formation Research Articles

Boosting miniaturization in clinical analysis: determination of bisphenols in human serum and urine by miniaturized stir bar sorptive dispersive microextraction.

In this work, a miniaturized and sustainable method for the determination of endocrine-disrupting bisphenols in human serum and urine employing the miniaturized stir bar sorptive dispersive microextraction (mSBSDME) approach has been developed. As bisphenols are conjugated in the human body to their glucorinated and sulfated forms, an enzymolysis employing a commercial mixture of β-glucuronidase and arylsulfatase was carried out prior to the microextraction procedure to determine their total content. A magnetic covalent organic framework (COF) was employed as thesorbent to carry out the extraction of the analytes from the biological matrixes, showing good extraction performance dueto its hydrophobic, π-π, and dipole-dipole interactions with the analytes. As instrumental detection, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed to achieve good sensitivity and selectivity. The method was validated for both matrixes, showing good linearity at least up to 100 ng mL-1, limits of detection in the low ng mL-1 range, good precision values (relative standard deviations below 15%), and good accuracy (relative recoveries between 80 and 127%). In order to show the applicability of the developed method, five samples from female volunteers were analyzed with the final aim of offering a practical tool for monitoring the female population's exposure to these highly endocrine-disrupting compounds. This new procedure enhances the implementation of miniaturized sample preparation approaches in biological samples for clinical analysis, giving special relevance to the sustainability of the method.

Antimony Vaporization and Condensation in Simulated Flash Smelting Off-Gas Train Conditions

AbstractAntimony is one of the most deleterious impurity elements in copper smelting and has a strong tendency to vaporize in the smelting furnace resulting in an enrichment of antimony in smelter flue dusts. The vaporization and condensation behavior of antimony species was studied in dust-free conditions simulating the off-gas train of a Flash Smelting Furnace at temperatures below 1273 K (1000 °C). The influences of the oxygen partial pressure and the condensate formation temperature on the characteristics of the precipitated antimony species were determined. It was found that practically all the vaporized antimony species precipitated between 853 K and 546 K (580 °C and 273 °C) and that a higher oxygen partial pressure favored precipitation at higher temperatures. The formation of antimony sulfate, which thermodynamically is the most stable antimony species in the studied conditions at temperatures below approximately 723 K (450 °C), was found to be kinetically constrained and the vaporized antimony species precipitated as oxides or sulfides depending on the oxygen partial pressure and the precipitate formation temperature.

Formation of a “Coat” of Copper Sulfate Around the Copper Cathode Depending on the Voltage Between the Electrodes in an Aqueous Suspension

This article studies the process of formation of copper sulfate crystallohydrate (CuSO4×5H2O) in an aqueous suspension when voltage is applied to copper electrodes. The factors influencing the intensity of the formation of copper sulfate, including the applied voltage, the distance between the electrodes and the composition of the water, are considered. Copper electrodes measuring 10×2 cm was used in the experiments. The distance between the electrodes varied from 2 to 10 cm. The electrodes were supplied with a voltage in the range from 2 to 29 V. The results of experiments, an analysis of the influence of various parameters on the crystallization process, as well as a discussion of possible reaction mechanisms are presented.

Positive Feedback between Partitioning of Carbonyl Compounds and Particulate Sulfur Formation during Haze Episodes.

Carbonyl compounds are important precursors of aqueous aerosols in the atmosphere, while their gas-particle partitioning behaviors and roles in particulate sulfur formation are poorly understood. In this study, we investigate the partitioning of five carbonyl compounds (formaldehyde, acetaldehyde, acetone, glyoxal, and methylglyoxal) during haze episodes in Beijing, China. On haze days, the values of field-derived effective Henry's law coefficients (KHf) on aerosols for these carbonyl compounds are 106-108 M atm-1, which are significantly higher (102-104 times) than those in pure water. Sulfate is observed to have a pronounced "salting-in" effect on these carbonyl compounds, resulting in at least 1-order-of-magnitude increase in their particle-phase concentrations. Parameterization schemes for their partitioning in the ambient aerosols were provided and applied to the multiphase chemical box model (RACM2-CAPRAM). When incorporated into the field-derived parametrization, the model significantly increased hydroxymethanesulfonate (HMS) production by 50-fold compared to using the parameters obtained in pure water, increasing from 2.6 × 10-2 to 1.23 μg m-3 h-1. The formed HMS can facilitate sulfate formation in turn through further oxidation by OH radicals and enhance aerosol hygroscopicity. These findings indicate a positive feedback loop between the partitioning of carbonyl compounds and particulate sulfur formation during haze episodes, providing new insights for controlling particulate pollution and reducing SO2 levels in urban areas.

Effect of Different Zn Concentrations on Crop Growth and Root Nodulation in Yard-Long Bean (Vigna unguiculata L.)

An experiment was conducted to study the effect of Zinc (Zn) as a micronutrient on growth and nodulation in Vigna unguiculata L. The experiment was carried out as a pot experiment in the Crop Farm, Faculty of Agriculture, Palachcholai, Eastern University, Sri Lanka from August to November 2023. The experiment was laid out in Complete Randomized Design with six treatments and four replicates. The treatments are T1 (Control), T2 (50 mg ZnSO4/kg soil), T3 (100 mg ZnSO4/kg soil), T4 (150 mg ZnSO4/kg soil), T5 (200 mg ZnSO4/kg soil) & T6 (250 mg ZnSO4/kg soil). The experiment used source of Zinc in the form of Zinc Sulphate (ZnSO4,5H2O) which yard-long bean plants can grow. The experiment results showed that, T2 treatment, the soil treated with 50 mg ZnSO4/kg soil significantly increase the Plant height, Chlorophyll content, Leaf area, Fresh weight of shoot & root, Dry weight of shoot & root, Number of nodules, Effective nodule percentage, as well as Soil respiration compared to the other treatments. However, beyond the level of 200 mg ZnSO4/kg soil, reduces the growth & nodulation of Vigna unguiculata L. and this shows that the level 200 mg ZnSO4/kg soil and beyond that level were the toxic level to the Vigna unguiculata L. Accordingly, the treatment T2 (50 mg ZnSO4/kg soil) was at the micronutrient level of Zn concentration which involved in many key cellular functions and show the best positive effect on growth and nodulation in Vigna unguiculata L. The results clearly indicate that, Zn can be use as a micronutrient up to a trace level in inducing plant growth and nodulation. However, at higher levels of Zn may act as heavy metal and cause phyto-toxicity in plants.

A fingerprint of source-specific health risk of PM2.5-bound components over a coastal industrial city

The influence of specific local land-use activities (continuously redistributing elements across environments) and environmental conditions (altering the chemical composition of airborne particulate matter) on the intrinsic health risk of PM2.5 exposure is sparsely reported. To fill this gap, we employed a novel integrated approach to address the influence of short-term changes in source-specific PM2.5 composition on the exposure-response risk, while controlling for weather conditions. We combine receptor-based source apportionment with conditional logistic regression in a space-time-stratified case-crossover design. This approach is different from previous studies as it: i) controls the impact of spatiotemporal variations in air pollution and human mobility using multilocation-specific fixed and disjointed space-time strata ii) addresses the spatial heterogeneity of personal exposure separating its variable effect from other predictors by allowing different baseline hazards for each space-time stratum; iii) aligns case/control periods with strong/regular episodes of source-specific PM-multipollutant fingerprint contributions rather than health outcomes. This enabled comprehensive examination of the association between source-specific PM2.5-bound species and cardiorespiratory disease hospitalizations. The epidemiological findings were that primary anthropogenic emissions [industrial (ORs 2.5 – 4.8)] were associated with higher 1-day moving average PM-induced risks. Natural-related sources [fresh / aged sea salt aerosol, dust, soil resuspension] and secondary sulfate formation were consistently associated with higher health risks (ORs 1.0 – 1.54) after 1 to 5-days since exposure. The results emphasize the importance of source-specific air quality management in complex areas and our research provides an adaptable universal tool to support targeted place-based policy interventions to mitigate air pollution impacts on health.

The Gypsum Influence on the Formation of Secondary Phases During Autoclave Leaching of Gold-Bearing Concentrates and the Silver Recovery Using Cyanidation.

Autoclave leaching of sulfide concentrates may produce various ferric secondary phases, depending on the arsenic content and temperature. Silver is converted to argentojarosite, from which it is not recoverable by standard cyanidation methods. To increase silver recovery, it is necessary to reduce the argentojarosite formation during autoclave leaching. This study was devoted to the influence of gypsum on the formation of secondary phases of ferric arsenate and the subsequent recovery of gold and silver by cyanidation. The addition of gypsum at a consumption of 0.1 g/g(concentrate) helped to increase silver extraction from 13.4 to 98% at cyanidation. Gold recovery was 99%. An increase in gypsum consumption contributed to the ferric arsenate sulfate formation with an increased sulfate sulfur content, and a decrease in the As/S(sulfate) molar ratio in the cake from 3.7 to 0.88 contributed to an increase in silver extraction at cyanidation of up to 98%. Basic ferric sulfate is not formed in this case, since according to EDS mapping, the distribution of arsenic and sulfur over ferric-containing particles is uniform. According to TCLP, stable, sparingly soluble ferric arsenate phases are formed and the cake obtained after cyanidation is stable and suitable for disposal, since the final arsenic concentration in the solution was 0.45 mg/dm3.

Understanding the production and reduction of barium sulfate crystals through the use of additives and a controlled stirring rate

Barium sulfate crystals are minerals responsible for scaling in piping systems. Controlling the growth of these crystals can use additives (FeCl2 and SrCl2) and varying agitation speeds. The research was to optimize the impact of additives and agitation speed on the results of crystal form using RSM through Minitab 19 with Box-Behnken Design. The optimum conditions using additive FeCl2 at a concentration of 25 ppm, a stirring speed of 120 rpm for 30 minutes, and a coefficient of determination (R2) of 90.995 provided 0.4485 gr of barium sulfate crystals. The optimum conditions, however, used SrCl2 additives at a concentration of 20.2049 ppm and a stirring speed of 459.394 rpm for 30 minutes, yielding 0.4345 g of barium sulfates with a coefficient of determination (R2) of 91.41%. The results of crystallizing barium sulfate without additives appear to be superior to those obtained with additives in terms of production. In contrast, additives of FeCl2 and SrCl2 can inhibit barium sulfate formation, resulting in a reduction in crystal mass

Cupric citrate supplementation improves growth performance, nutrient utilization, antioxidant capacity, and intestinal microbiota of broilers.

This study aimed to examine the impact of cupric citrate on broilers and compare it with the copper sulfate groups and a control group. A total of 360 1-day-old Ross 308 broilers were randomly assigned into 5 groups, each with 6 replicates of 12 broilers per treatment. The control group was fed a basal diet without any copper supplementation. In contrast, the other groups received basal diets supplemented with either 50 mg/kg (CS-50) or 100 mg/kg (CS-100) of copper in the form of copper sulfate, or 50 mg/kg (CC-50) or 100 mg/kg (CC-100) of copper in the form of cupric citrate, for a period of 42 days. The results showed that copper supplementation affected the average daily gain from day 1 to 21 (p = 0.026) and day 1 to 42 (p = 0.025) in a source-dependent manner. Copper source also influenced the energy digestibility (p = 0.004), with the CC-100 being the most effective treatment. Notably, birds in the CC-100 groups had significantly reduced concentrations of Escherichia coli (p < 0.05) in the cecum, and the Lactobacillus in the ileum, compared to the control group. Dietary copper supplementation also increased the pH in the duodenum (p < 0.05) irrespective of the sources and levels. In addition, the source of copper affected the activities of ceruloplasmin (p = 0.014) and Cu-Zn superoxide dismutase (p = 0.025) in the serum, with the CC-100 group showing the highest levels of both enzymes. Copper supplementation generally improves the growth, nutrient utilization, intestinal microflora, gastrointestinal pH, and antioxidant defences of broilers. Moreover, cupric citrate is as effective as copper sulfate even at equal or lower concentrations.

Biochemistry of Redox-Active Sulphur Compounds in Mammalian Cells and Approaches to Detecting Them

The discovery of new classes of regulatory molecules in human and animal metabolism always leads to a large-scale study of their properties in the context of biochemistry, physiology, and pharmacology. About 20 years ago, hydrogen sulfide (H2S) and its derivatives – active sulfur forms (ASFs): persulfides, polysulfides, nitrosothiols, sulfenic acids, etc. – became one of such classes of molecules. The participation of ASFs in a variety of physiological and pathological processes, such as regulation of vascular tone, inflammation, long-term potentialization in the central nervous system, etc., has been shown. Changes in ASF levels or patterns of modification of their targets are associated with a wide range of pathologies: cardiovascular, oncologic, neurodegenerative, and others. For a part of these processes, mechanisms have been studied that involve direct modification of regulatory (NF-κB, Keap1) or effector (GAFD, eNOS, TRPA1) proteins through reactions of cysteine residues and metal-containing centers with APS. The presence of different regulated enzymatic systems producing APS and numerous molecular targets allows us to consider H2S and its derivatives as an important class of small regulatory molecules. H2S is counted among the so-called “gas transmitters”, along with nitric oxide(II) and carbon monoxide. Over the last 20 years, a huge amount of data on the biochemistry of these compounds and approaches to their study has been accumulated.

The Dissolution Behavior of Pyrite and Chalcopyrite During Low-Temperature Pressure Oxidation: Chalcopyrite Influence on Pyrite Oxidation

The research of this paper was carried out on the low-temperature (100 ± 2 °C) pressure (0.2–0.8 MPa) leaching of pyrite, chalcopyrite and their mixture. According to experiments on chalcopyrite dissolution, increasing the oxygen pressure from 0.2 up to 0.8 MPa had a slight effect on chalcopyrite dissolution. Oxygen pressure and initial sulfuric acid concentration in the range of 10–50 g/L had the greatest positive effect on the pyrite oxidation. The SEM and EDX mappings indicate the chalcopyrite and pyrite surfaces to be passivated by elemental sulfur. The oxidation degree of pyrite in its mixture with chalcopyrite increased significantly from 54.5 up to 80.3% in 0–240 min. The reaction time is relative to the dissolution of the individual mineral, while the dissolution of chalcopyrite remained virtually unchanged. The addition of Cu (II) and Fe (III) ions does not influence pyrite dissolution when chalcopyrite is added in a leaching process, which can be explained by the formation of an electrochemical link between the minerals. The positive effect of chalcopyrite addition is associated with a decreased formation of elemental sulfur on the surface of pyrite. The described method can be used for the hydrometallurgical processing of copper raw materials with increased pyrite content, as well as for the pretreatment of copper concentrates with gold-rich pyrite concentrates to increase the recovery of gold and silver.

Comparison of the Results of Modeling Pulmonary Fibrosis in Sprague Dawley Rats by Intratracheal Administration of Bleomycin in the Form of Sulfate and Chloride at a Dose of 3 mg/kg.

Background/Objectives: Intratracheal administration of bleomycin (BLM) to laboratory rodents is a standard, widely used technique used to model pulmonary fibrosis (PF). BLM, as a modeling agent, is produced mainly in the form of two salts-sulfate and chloride. We compared the results of modeling PF in SD rats by intratracheal administration of BLM sulfate and BLM chloride. Methods: Healthy mature male SD rats were used. PF was modeled by intratracheal administration of BLM sulfate and BLM chloride at a dose of 3 mg/kg. The criteria for the development of PF included body weight gain, changes in respiratory parameters, relative lung weight, cellular composition of broncho-alveolar fluid (BALF), histological assessment of the severity of PF with trichrome Masson staining. Results: Intratracheal administration of both BLM salts led to the development of pronounced PF, which was determined by changes in all of the measured parameters relative to control animals. There were no significant differences between the BLM sulfate and BLM chloride groups in body weight gain, hydroxyproline content, and histological evaluation. However, significant differences were identified in the cellular composition of BALF-a significant increase in alveolar macrophages and neutrophils levels in animals treated with BLM sulfate. Conclusions: Intratracheal administration of both BLM salts led to the development of severe PF; however, the inflammatory process in animals receiving BLM sulfate was more pronounced and prolonged than in animals receiving BLM chloride, which in the former, when observed more than 21 days after modeling, can lead to more severe PF.

From Ions to Crystals: A Comprehensive View of the Non-Classical Nucleation of Calcium Sulfate.

After years ofintensive research andnumerous important observations, our understanding of the early stages of crystallization is still limited due to the complexity of the underlying processes and their elusive character. In the present work, we provide a detailed view on the nucleation of calcium sulfate mineralization - an abundant mineral with broad use in construction industry - in aqueous systems at ambient conditions. As experimental basis, a co-titration procedure with potentiometric, turbidimetric and conductometric detection was developed, allowing solution speciation and the formation of crystallization precursors to be monitored quantitatively as the level of nominal (super)saturation gradually increases. The nature and spatiotemporal evolution of these precursors was further elucidated by time-resolved small-angle X-ray scattering (SAXS) and analytical ultracentrifugation (AUC) experiments, complemented by cryogenic transmission electron microscopy (cryo-TEM) as a direct imaging technique. The results reveal how ions associate into nanometric primary species, which subsequently aggregate and develop anisotropic order by intrinsic structural reorganization. Our observations challenge the common understanding of fundamental notions such as the nucleation barrier or the meaning of supersaturation, with broad implications for mineralization phenomena in general and the formation of calcium sulfate in geochemical settings and industrial applications in particular.

Isotopic signature of N2O produced during sulfur‐ and thiosulfate‐driven chemoautotrophic denitrification in freshwaters

AbstractChemoautotrophic denitrification plays an important role in nitrogen removal and the formation of a greenhouse gas (N2O) in aquatic environments. Natural stable isotopes support the tracing of nitrogen sources and the identification of biogeochemical processes in field research. However, the isotopic characteristics of N2O produced during chemoautotrophic denitrification have not been investigated so far. In this study, we analyzed isotopic signatures of nitrate and N2O in sulfur‐ and thiosulfate‐dependent denitrifying enrichments obtained from freshwater lakes. Chemoautotrophic denitrification exhibited a nitrate isotope pattern similar to heterotrophic denitrification: the 18ε/15ε‐nitrate followed a ratio close to 1. However, chemoautotrophic denitrification produced N2O with lower δ15N, δ18O, and higher site preference (SP = δ15Nα‐δ15Nβ) values, compared to heterotrophic denitrification. The SP value, approximately 5.1‰, was characteristic in detecting chemoautotrophic denitrification driven by different sulfur forms. δ18O varied with specific electron donors, around 20‰ and 40‰ during sulfur‐ and thiosulfate‐dependent denitrification, respectively. The unique N2O isotope characteristics were likely regulated by nitric oxide reductases of Burkholderiaceae populations during sulfur‐dependent denitrification and Sulfurovum during thiosulfate‐dependent denitrification. These findings improve our understanding of N2O production processes and have important implications for predicting N2O emissions at a greater spatial and temporal resolution.

Element behavior during autoclave oxidation of polymetallic sulfide flotation concentrate containing tungsten and molybdenum

In this paper, we investigate the behavior of associated elements (tungsten, molybdenum, and bismuth) contained in a sulfide gold-bearing concentrate during its autoclave oxidation. The process is studied using a sulfide flotation concentrate, crushed to a particle sieve mesh size of minus 0.045 mm and containing 22.1 g/t of gold, 133.2 g/t of silver, 2.7% of tungsten, 13% of molybdenum, and 0.7% of bismuth. The process was carried out in a 2 dm3 autoclave at a temperature of 220ºC and an oxygen partial pressure of 0.7 MPa. The concentrations of sulfuric acid and iron ions in the solution were determined by titrimetric analysis. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentrations of bismuth, tungsten, molybdenum, copper, silver, and arsenic in the solution, as well as the content of bismuth, tungsten, molybdenum, copper, arsenic, lead, and iron and sulfur forms in the cake. The cake was also examined using diffraction analysis. Experiments on cyanidation of oxidized cake were carried out in the pH range of 10.0–10.5 and a NaCN concentration of 1 g/dm3 with a PuroliteS992 ion exchange resin for 24 h. Autoclave oxidation experiments showed the sulfide oxidation degree to be higher than 99%. Extraction of molybdenum into solution in the form of [MoO2(SO4)n]-(2n-2) and MoO 2+ amounted to 95%. The decrease in the solid mass led to an increase in the concentration of bismuth and tungsten in the cake, with their contents reaching 1.66% and 12.7%, respectively. The main phases in the cake were established to be scheelite, anhydrite, plumboyarosite, and bedantite. The extraction of precious metals at the subsequent cyanidation stage amounted to 97.5% of gold and 91.6% of silver. Therefore, autoclave cyanide processing of sulfide gold-containing concentrates leads to a molybdenum extraction in the autoclave oxidation solution at the level of 95%. During cyanidation, more than 90% of gold and silver are extracted. Due to the significant amount of tungsten (17%), bismuth (0.9%), lead (5.3%), and molybdenum (3.3%), the obtained cake cannot be considered a waste product.

Preparation of Titanium Dioxide (TiO&lt;sub&gt;2&lt;/sub&gt;) from Waste of Polymetallic Ore Processing &lt;i&gt;via&lt;/i&gt; Sulfurization Treatment

Various experimental conditions were applied to extract titanium oxide from the waste of polymetallic ore. X-ray diffraction (XRD) analysis confirms that the waste of polymetallic ore contains including various minerals such as almandine (Fe,Mg,Ca)3Al2Si3O12, brownmillerite (FeAlO3(CaO)2), quartz (SiO2), magnetite (Fe3O4). Using H2SO4 acid with a concentration of 93% in the S/L mass ratio of 1:1.5 at 140 °C is suggested as an optimum reaction condition. Its hydrolysis subsequently leads to the formation of the titanyl sulfate (TiOSO4), and relatively pure titanium oxide is obtained through precipitation and calcination at 600 °C. The observed band gap value of 3.2 eV for the obtained TiO2 corresponds to the typical band gap value of anatase-type TiO2. We calculated the crystallite size of extracted anatase-type titanium oxide according to the Debye-Scherrer equation it was determined to be 96.35 nm. Fully reflecting X-ray fluorescence (XRF) determined that the purity of extracted TiO2 is 93.18%. This report presents a newly developed process that enables the production of relatively high-purity TiO2 (93.18%) from the waste of polymetallic ore (TiO2 5.39%) by a simple sulfurization process.

High temperature environmental scanning electron microscopy characterization of transient phase formation during conversion of simulated nuclear waste feed to glass

In-situ High-Temperature Environmental Scanning Electron Microscopy (HT-ESEM) is used to characterize the transient phases formed during the melting of complex glass batch mixtures representing simulated nuclear waste feeds. The first phenomenon that occurs is the formation of oxyanionic salt melt, followed by the reaction of oxyanionic salts with refractory grains containing Si, Al, or Mg through surface reactions to form a molten alkali-alumino-boro-silicate phase. The onset temperatures of gas bubble formation and primary foaming are directly determined from the HT-ESEM measurements. The formation of sulfate lakes as well as the formation of high-temperature transient phases floating at the sample surface are also directly observed and identified. Convection currents are observed and their consequences on glass homogenization are discussed.

Study of the possibilities of determining mobile sulfur by physical-chemical and chemical methods in various substrates in the presence of orthanilic K

&lt;p&gt;The article presents the results of testing the developed method for determining mobile sulfur in wood ash and various soil substrates. Determination of sulfur in sulfate form in presence of orthanilic K is possible due to the indicator’s ability to form coloured complexes with Ba&lt;sup&gt;2+&lt;/sup&gt; ion. We examined the ranges of volumetric and photometric determination. The accuracy of the analysis was determined by comparison with a certified method. We present optimal conditions for the successful determination of the mobile sulfur with the titration and with spectrophotometric method. The results of experiments confirming the capabilities of the method under study are presented.&lt;/p&gt;

Nutrient removal performance and the nitrogen-sulfur conversion pathways in sulfur-iron based biofilter under acidic/alkaline conditions

The nitrate and phosphate removal in sulfur based (Vp) and sulfur-iron based autotrophic denitrification systems (Sp) with sponge iron as the iron source was investigated under different pH (6–9). In this study, Sp (>98 %) and Vp (>97 %) had higher nitrate removal efficiency at pH 7–8 and the highest phosphate removal efficiency (94.9 % ± 3.57 %) at pH 6. The flow cytometry detection revealed that the cell integrity was damaged due to the formation of iron crusts at pH 6, which resulted in irreversible inhibition in Sp. Electron transfer and nitrogen transformation showed that compared with the sustained inhibition of denitrification at pH 6, the inhibition at pH 9 occurred mainly in the initial 0–2 h due to the enhanced flow of electrons toward the formation of biological element sulfur (Sbio0). Coupled sponge iron promoted the adsorption and reduction of NO2−/N2O and reduced N2O emissions. Metatranscriptomics analysis showed that significant upregulation of key gene expression for nitrogen and sulfur metabolism in Sp, with complex regulatory mechanisms enhancing system stability and performance. Acidic conditions reduced the abundance of denitrification and sulfur oxidation functional genes. However, alkaline conditions (pH of 9) mainly caused the decreased abundance of denitrification functional genes, which was favorable for accumulation of Sbio0. This study provides a theoretical basis for the stable operation and regulation of the sulfur-iron based autotrophic denitrification process.

PSLBII-3 Influence of iron supplementation on insulin and glucose dynamics in horses

Abstract Iron is an essential micromineral involved in various physiological functions such as oxygen transport. The National Research Council’s Nutrient Requirements of Horses has iron requirements set at 400 mg iron daily for a 500 kg horse at maintenance; however, a survey found that Thoroughbreds consumed well over the daily requirement at 3,900 mg of iron from hay and grain alone. Additionally, a previous study has found a correlation between hyperinsulinemia and increased ferritin, an indicator of iron body stores. Therefore, the objective of the present study was to determine the effects of iron supplementation on body iron stores as well as insulin and glucose dynamics. It was hypothesized that iron supplementation would influence body iron stores and insulin and glucose responses. Mixed-breed geldings [n = 12; 558.9 ± 74.4 kg body weight (BW)] were housed individually for the study. Horses were fed 2% of their BW in grass hay and an iron-free vitamin mineral supplement, consuming an average of 600 mg of iron daily for the first 28 d (Hay Phase). Horses were then assigned to continue on the hay diet (CTRL; n = 4) or an iron-supplemented diet (IRON; n = 8), in which an oral iron supplement was given daily in the form of ferrous sulfate, with IRON horses consuming an average of 4,000 mg of iron daily for 28 d (Supplement Phase). Oral sugar tests (OSTs) were performed at the beginning of the study as well as the end of each phase, using a 0.45 mL/kg of BW Karo Light Syrup dose to determine insulin response, with jugular venous samples taken prior to the dose and 60 min after. All statistical analysis was performed in GraphPadPrism Version 10.2.0 (GraphPad Software, Boston, MA), using analysis of variance for repeated measures and correlation analysis. All OSTs throughout the study had a significant time effect (P &amp;lt; 0.05) for both insulin and glucose. There was a time X treatment trend (P = 0.1) for insulin during the Supplement Phase and when using multiple comparisons, insulin response was significantly greater (P &amp;lt; 0.0007) at 0 versus 60 min in IRON horses. Although there was no correlation found between 60-min insulin and ferritin concentrations in both IRON and CTRL horses, mean ± SD insulin and ferritin in the IRON group were 23.6 ± 10 uU/mL and 570 ± 195.8 ng/mL, respectively, while in the CTRL group these were 12.7 ± 2.9 uU/mL and 453 ± 31.1 ng/mL, respectively. In conclusion, iron supplementation with an inorganic form at 10 times the daily requirement appears to result in increased insulin responses as well as body iron stores. Further research needs to determine if feeds naturally enriched in iron impact glucose metabolism.