Articles de revues : « Cycle of iron and other trace metals »

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Tan, Maxine H., Sarah R. Smith, Kim K. Hixson, Justin Tan, James K. McCarthy, Adam B. Kustka et Andrew E. Allen. « The Importance of Protein Phosphorylation for Signaling and Metabolism in Response to Diel Light Cycling and Nutrient Availability in a Marine Diatom ». Biology 9, n^o 7 (6 juillet 2020) : 155. http://dx.doi.org/10.3390/biology9070155.

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Diatoms are major contributors to global primary production and their populations in the modern oceans are affected by availability of iron, nitrogen, phosphate, silica, and other trace metals, vitamins, and infochemicals. However, little is known about the role of phosphorylation in diatoms and its role in regulation and signaling. We report a total of 2759 phosphorylation sites on 1502 proteins detected in Phaeodactylum tricornutum. Conditionally phosphorylated peptides were detected at low iron (n = 108), during the diel cycle (n = 149), and due to nitrogen availability (n = 137). Through a multi-omic comparison of transcript, protein, phosphorylation, and protein homology, we identify numerous proteins and key cellular processes that are likely under control of phospho-regulation. We show that phosphorylation regulates: (1) carbon retrenchment and reallocation during growth under low iron, (2) carbon flux towards lipid biosynthesis after the lights turn on, (3) coordination of transcription and translation over the diel cycle and (4) in response to nitrogen depletion. We also uncover phosphorylation sites for proteins that play major roles in diatom Fe sensing and utilization, including flavodoxin and phytotransferrin (ISIP2A), as well as identify phospho-regulated stress proteins and kinases. These findings provide much needed insight into the roles of protein phosphorylation in diel cycling and nutrient sensing in diatoms.

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Chang, Xuan, et Yingxia Li. « Using a Multimedia Aquivalence Model to Evaluate the Environmental Fate of Fe, Mn and Trace Metals in an Industrial City, China ». Water 12, n^o 6 (2 juin 2020) : 1580. http://dx.doi.org/10.3390/w12061580.

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The rapid expansion of urban impervious surface areas complicates urban-scale heavy metal circulation among various environmental compartments (air, soil, sediment, water, and road dust). Herein, a level III steady-state aquivalence model evaluated the fate of heavy metals in Nanjing, China. Iron was the most abundant heavy metal in all environmental compartments, while cadmium was the rarest. Most simulated concentrations agreed with measured values within three logarithmic residuals. In the simulated heavy metal cycle, industrial emission contributed almost the entire input, whereas sediment burial was the dominant output pathway. The transfer fluxes between bottom sediment and water were the highest. Thereinto, the contribution of sediment resuspension for Fe and Mn was significantly higher than that to the other metal elements, which could partly explain why Fe and Mn are the major blackening ingredients in malodorous black rivers. Road dust was also an important migration destination for heavy metals, accounting for 3–45%, although soil and sediment were the main repositories of heavy metals in the urban environment. The impact of road dust on surface water should not be neglected, with its contribution reaching 4–31%. The wash-off rate constant W for road dust–water process was proved to be consistent with that for film–water and was independent of the type of heavy metals. Sensitivity analysis highlighted the notable background value effect on Fe and Mn.

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Rahman, Md Lutfor, Zhi Jian Wong, Mohd Sani Sarjadi, Sabrina Soloi, Sazmal E. Arshad, Kawi Bidin et Baba Musta. « Heavy Metals Removal from Electroplating Wastewater by Waste Fiber-Based Poly(amidoxime) Ligand ». Water 13, n^o 9 (30 avril 2021) : 1260. http://dx.doi.org/10.3390/w13091260.

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An efficient and economical treatment technology for heavy metal removal from the electroplating wastewaters is needed for the water purification. Therefore, pure cellulosic materials were derived from two waste fiber (pandanus fruit and durian rind) and conversion of the cellulose into the poly(acrylonitrile)-grafted material was accomplished by free radical grafting system. Thereafter, poly(amidoxime) ligand was produced from the grafted materials. Sorption capacity (qe) of several toxic metals ions was found to be high, e.g., copper capacity (qe) was 298.4 mg g−1 at pH 6. In fact, other metal ions, such as cobalt chromium and nickel also demonstrated significant sorption capacity at pH 6. Sorption mechanism played acceptable meet with pseudo second-order rate of kinetic pattern due to the satisfactory correlation with the experimental sorption values. A significant correlation coefficient (R2 > 0.99) with Langmuir model isotherm showed the single or monolayer sorption occurred on the surfaces. The reusability study showed that the polymer ligand can be useful up to six cycles with minimum loss (7%) of efficiency and can be used in the extraction of toxic metal ions present in the wastewaters. Therefore, two types of electroplating wastewater were used in this study, one containing high concentration of copper (23 ppm) and iron (32 ppm) with trace level of others heavy metals (IWS 1) and another containing high concentration of copper (85.7 ppm) only with trace level of others heavy metals (IWS 2). This polymeric ligand showed acceptable removal magnitude, up to 98% of toxic metal ions can be removed from electroplating wastewater.

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Sánchez-España, Javier, et Jesús Reyes. « Comparing Schwertmannite and Hydrobasaluminite Dissolution in Ammonium Oxalate (pH 3.0) : Implications for Metal Speciation Studies by Sequential Extraction ». Minerals 9, n^o 1 (17 janvier 2019) : 57. http://dx.doi.org/10.3390/min9010057.

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The “poorly crystalline iron oxy-hydroxides” are one of the most reactive and environmentally important fractions in soils and sediments due to the association of many toxic elements associated with these minerals. The metal content of this fraction in sequential extraction procedures is usually evaluated by dissolution in ammonium oxalate ([NH4]2C2O4·H2O) at pH 3.0 and 25 ᵒC [1–12]. Such chemical treatment, however, may also dissolve other mineral phases of comparable reactivity, which can lead to wrong interpretations of mineral carriers for specific metals. In this study, we compare the dissolution kinetics of schwertmannite and hydrobasaluminite, two minerals of comparable crystallinity and reactivity that play a major role in the mobility of many trace metals in waters and sediments affected by acid mine drainage (AMD). We first synthesized these two minerals in the laboratory by partial neutralization of two different metal-rich mine waters, and then we applied the standard protocol of ammonium oxalate dissolution to different specimens; the solutions were periodically sampled at intervals of 2, 5, 10, 15, 30 and 60 min to compare (i) the kinetics of mineral dissolution, and (ii) the metals released during dissolution of these two minerals. The results indicate a very similar kinetics of mineral dissolution, though hydrobasaluminite exhibited a faster rate. Some toxic elements such as As, Cr or V were clearly bonded to schwertmannite, while many others such as Cu, Zn, Si, Co, Ni and Y were clearly linked to hydrobasaluminite. These results suggest that studies linking the mobility of many elements with the Fe cycle in AMD-affected soils and sediments could be inaccurate, since these elements could actually be associated with Al minerals of poor crystallinity. The step of ammonium oxalate dissolution in sequential extraction studies should be best described with a more general term such as “low-crystallinity oxy-hydroxides”.

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Facey, Jordan A., Simon C. Apte et Simon M. Mitrovic. « A Review of the Effect of Trace Metals on Freshwater Cyanobacterial Growth and Toxin Production ». Toxins 11, n^o 11 (5 novembre 2019) : 643. http://dx.doi.org/10.3390/toxins11110643.

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Cyanobacterial blooms are becoming more common in freshwater systems, causing ecological degradation and human health risks through exposure to cyanotoxins. The role of phosphorus and nitrogen in cyanobacterial bloom formation is well documented and these are regularly the focus of management plans. There is also strong evidence that trace metals are required for a wide range of cellular processes, however their importance as a limiting factor of cyanobacterial growth in ecological systems is unclear. Furthermore, some studies have suggested a direct link between cyanotoxin production and some trace metals. This review synthesises current knowledge on the following: (1) the biochemical role of trace metals (particularly iron, cobalt, copper, manganese, molybdenum and zinc), (2) the growth limitation of cyanobacteria by trace metals, (3) the trace metal regulation of the phytoplankton community structure and (4) the role of trace metals in cyanotoxin production. Iron dominated the literature and regularly influenced bloom formation, with 15 of 18 studies indicating limitation or colimitation of cyanobacterial growth. A range of other trace metals were found to have a demonstrated capacity to limit cyanobacterial growth, and these metals require further study. The effect of trace metals on cyanotoxin production is equivocal and highly variable. Better understanding the role of trace metals in cyanobacterial growth and bloom formation is an essential component of freshwater management and a direction for future research.

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Baraj, Besnik, Luis Felipe Niencheski, Gilberto Fillmann et Luciano Hermanns. « Biochemical normalization of trace metals in Arctocephalus australis ». Brazilian Journal of Oceanography 57, n^o 1 (mars 2009) : 1–6. http://dx.doi.org/10.1590/s1679-87592009000100001.

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Initially, the heart concentration data does not seem relevant for use as a bioindicator, mainly due to its low concentration level. After applying a normalizing procedure, the heart results were a better Hg bioindicator (preconcentration coefficient 43.1) than those of the kidney (preconcentration coefficient 8.6). Cadmium preconcentration coefficients were 128.1, 195.3 and 5.2 for liver, kidney and heart, respectively, demonstrating the high accumulative capacity especially for the liver and kidneys. Iron is proposed as a normalizing element for the definiton of the regional natural biochemical population of the metals. In general, positive correlation coefficients were found between Fe and other metals.

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Scales, W. E., A. J. Vander, M. B. Brown et M. J. Kluger. « Human circadian rhythms in temperature, trace metals, and blood variables ». Journal of Applied Physiology 65, n^o 4 (1 octobre 1988) : 1840–46. http://dx.doi.org/10.1152/jappl.1988.65.4.1840.

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The literature supports the concept that circadian changes in body temperature reflect changes in the thermoregulatory set point. We were interested in studying the relationship between the circadian rhythm in body temperature and 24-h variations in plasma concentrations of iron, zinc, circulating leukocyte counts, and plasma interleukin 1 (IL-1) activity. Eight healthy men were studied for two separate 48-h sessions. Rectal temperature, plasma iron and zinc concentrations, plasma IL-1 activity, circulating leukocyte counts, and several other blood variables were monitored. Circadian rhythms in temperature, trace metals, and various leukocyte populations were demonstrated. The 24-h pattern of changes in plasma concentrations of iron and zinc approximate an inverse relationship with rectal temperature. Although we were unable to detect any IL-1 activity in human plasma collected at 4-h intervals, the daily changes in plasma trace metal concentrations and the variations in leukocyte populations may provide indirect evidence for a daily variation in local (e.g., in liver) or central nervous system release of IL-1.

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Bowell, Rob, Christopher Brough, Andrew Barnes et Arman Vardanyan. « Geometallurgy of Trace Elements in the Hrazdan Iron Deposit ». Minerals 11, n^o 10 (2 octobre 2021) : 1085. http://dx.doi.org/10.3390/min11101085.

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This study presents an evaluation of arsenic and other trace metals in the Hrazdan Iron-Ore project in Armenia using a methodology typically associated with Geometallurgical characterization. The principal host of the trace elements is pyrite and oxidized equivalents. Pyrite is a mineral of elemental concern as it has the potential to generate acidic pH in water that it contacts and thus mobilize metals of concern. In the Hrazdan deposit, there is a general excess of neutralizing carbonate minerals that result in adequate buffering of generated acid and limiting the mobility of metal cations in solution. However, metalloids that form oxyanions species such as those of arsenic or chromium tend to be more mobile in neutral to alkaline mine drainage. From the geometallurgical assessment of the mine waste, the results of the geochemical testwork can be explained and the information used to assess potential issues with mine waste storage, timing of metal release and provide a baseline for mitigation strategies.

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Makević, Vedrana, Luka de et Anđelija Ilić. « Essential trace metals in health and disease ». Medicinski podmladak 74, n^o 5 (2023) : 1–8. http://dx.doi.org/10.5937/mp74-43573.

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Essential trace metals (Fe, Zn, Cu, Mn, Mo, Co) are involved in high number of physiological and metabolic activities and therefore have a substantial role in organisms. Thus, their balance is tightly regulated by levels of absorption, transport, and storage in the organism. They can alter human health in both deficiency and overload conditions. On one hand, deficiency health problems are due to reduction of their physiological activities. On the other hand, Fe, Cu and Co are redox active metals and their increase can cause severe tissue damage through oxidative stress. Numerous well-established diseases like iron and copper deficiency anemia, hemochromatosis, Menkes and Wilson disease, acrodermatitis enteropathica are consequence of essential metal alterations. Nowadays, trace metals alterations are also found to be implicated in neurodegenerative disease, cancers, atherosclerosis, and diabetes. Those diseases represent enormous health problems in contemporary society and trace metals might help to further elucidate their pathogenesis and potentially even treatment. In the present study, essential trace metals kinetic and physiology are reviewed, as well as their roles in disease pathophysiology.

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Forsch, Kiefer O., Lisa Hahn-Woernle, Robert M. Sherrell, Vincent J. Roccanova, Kaixuan Bu, David Burdige, Maria Vernet et Katherine A. Barbeau. « Seasonal dispersal of fjord meltwaters as an important source of iron and manganese to coastal Antarctic phytoplankton ». Biogeosciences 18, n^o 23 (13 décembre 2021) : 6349–75. http://dx.doi.org/10.5194/bg-18-6349-2021.

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Abstract. Glacial meltwater from the western Antarctic Ice Sheet is hypothesized to be an important source of cryospheric iron, fertilizing the Southern Ocean, yet its trace-metal composition and factors that control its dispersal remain poorly constrained. Here we characterize meltwater iron sources in a heavily glaciated western Antarctic Peninsula (WAP) fjord. Using dissolved and particulate ratios of manganese to iron in meltwaters, porewaters, and seawater, we show that surface glacial melt and subglacial plumes contribute to the seasonal cycle of iron and manganese within a fjord still relatively unaffected by climate-change-induced glacial retreat. Organic ligands derived from the phytoplankton bloom and the glaciers bind dissolved iron and facilitate the solubilization of particulate iron downstream. Using a numerical model, we show that buoyant plumes generated by outflow from the subglacial hydrologic system, enriched in labile particulate trace metals derived from a chemically modified crustal source, can supply iron to the fjord euphotic zone through vertical mixing. We also show that prolonged katabatic wind events enhance export of meltwater out of the fjord. Thus, we identify an important atmosphere–ice–ocean coupling intimately tied to coastal iron biogeochemistry and primary productivity along the WAP.

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Dobrinas, Simona, Alina Soceanu, Gabriela Stanciu, Viorica Popescu et Luiza Georgiana Arnold. « Trace element levels of three mushroom species ». Analele Universitatii "Ovidius" Constanta - Seria Chimie 24, n^o 1 (1 juin 2013) : 39–42. http://dx.doi.org/10.2478/auoc-2013-0008.

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AbstractThe aim of this study was to determine Cu, Fe and Cr contents of three species of fresh mushrooms and canned mushrooms: white and brown champignon (Agaricus bisporus) and Pleurotus Ostreatus. Were analyzed various plant parts: stem, cap and cuticle of fresh mushrooms and only stem and cap for canned mushrooms. The levels of trace metals of mushroom samples collected from regions of Romania, Poland and Turkey were determined by UV/Visible spectrometry - standard addition method after digestion method. The contents of investigated trace metals in mushroom samples were found to be in the range of 0.01 - 2.26 mg/Kg for chromium, 2.02 - 430.67 mg/Kg for copper and 240.40 - 7952.89 mg/Kg for iron. The iron content was found to be higher than those of the other two minerals in all the samples. Mushrooms species in the highest levels of trace elements were found white champignon for Cu and Fe and brown champignon for Cr.

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D’Haese, Patrick C., Marie-Madeleine Couttenye, Ludwig V. Lamberts, Monique M. Elseviers, William G. Goodman, Iris Schrooten, Walter E. Cabrera et Marc E. De Broe. « Aluminum, Iron, Lead, Cadmium, Copper, Zinc, Chromium, Magnesium, Strontium, and Calcium Content in Bone of End-Stage Renal Failure Patients ». Clinical Chemistry 45, n^o 9 (1 septembre 1999) : 1548–56. http://dx.doi.org/10.1093/clinchem/45.9.1548.

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Abstract Background: Little is known about trace metal alterations in the bones of dialysis patients or whether particular types of renal osteodystrophy are associated with either increased or decreased skeletal concentrations of trace elements. Because these patients are at risk for alterations of trace elements as well as for morbidity from skeletal disorders, we measured trace elements in bone of patients with end-stage renal disease. Methods: We analyzed bone biopsies of 100 end-stage renal failure patients enrolled in a hemodialysis program. The trace metal contents of bone biopsies with histological features of either osteomalacia, adynamic bone disease, mixed lesion, normal histology, or hyperparathyroidism were compared with each other and with the trace metal contents of bone of subjects with normal renal function. Trace metals were measured by atomic absorption spectrometry. Results: The concentrations of aluminum, chromium, and cadmium were increased in bone of end-stage renal failure patients. Comparing the trace metal/calcium ratio, significantly higher values were found for the bone chromium/calcium, aluminum/calcium, zinc/calcium, magnesium/calcium, and strontium/calcium ratios. Among types of renal osteodystrophy, increased bone aluminum, lead, and strontium concentrations and strontium/calcium and aluminum/calcium ratios were found in dialysis patients with osteomalacia vs the other types of renal osteodystrophy considered as one group. Moreover, the concentrations of several trace elements in bone were significantly correlated with each other. Bone aluminum was correlated with the time on dialysis, whereas bone iron, aluminum, magnesium, and strontium tended to be associated with patient age. Bone trace metal concentrations did not depend on vitamin D intake nor on the patients’ gender. Conclusions: The concentration of several trace elements in bone of end-stage renal failure patients is disturbed, and some of the trace metals under study might share pathways of absorption, distribution, and accumulation. The clinical significance of the increased/decreased concentrations of several trace elements other than aluminum in bone of dialysis patients deserves further investigation.

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Facey, Jordan A., Jake P. Violi, Josh J. King, Chowdhury Sarowar, Simon C. Apte et Simon M. Mitrovic. « The Influence of Micronutrient Trace Metals on Microcystis aeruginosa Growth and Toxin Production ». Toxins 14, n^o 11 (21 novembre 2022) : 812. http://dx.doi.org/10.3390/toxins14110812.

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Microcystis aeruginosa is a widespread cyanobacteria capable of producing hepatotoxic microcystins. Understanding the environmental factors that influence its growth and toxin production is essential to managing the negative effects on freshwater systems. Some micronutrients are important cofactors in cyanobacterial proteins and can influence cyanobacterial growth when availability is limited. However, micronutrient requirements are often species specific, and can be influenced by substitution between metals or by luxury uptake. In this study, M. aeruginosa was grown in modified growth media that individually excluded some micronutrients (cobalt, copper, iron, manganese, molybdenum) to assess the effect on growth, toxin production, cell morphology and iron accumulation. M. aeruginosa growth was limited when iron, cobalt and manganese were excluded from the growth media, whereas the exclusion of copper and molybdenum had no effect on growth. Intracellular microcystin-LR concentrations were variable and were at times elevated in treatments undergoing growth limitation by cobalt. Intracellular iron was notably higher in treatments grown in cobalt-deplete media compared to other treatments possibly due to inhibition or competition for transporters, or due to irons role in detoxifying reactive oxygen species (ROS).

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Laan, Ramon G. W., Tona Verburg, H. Th Wolterbeek et Jeroen J. M. de Goeij. « Photodegradation of Iron(III)-EDTA : Iron Speciation and Domino Effects on Cobalt Availability ». Environmental Chemistry 1, n^o 2 (2004) : 107. http://dx.doi.org/10.1071/en04025.

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Environmental Context. Aquatic life requires access to sufficient nutrients and trace metals in the surrounding waters. Measuring the speciation (in solution or precipitated, free ionic or complexed) of trace metals is a traditional procedure to assess the potential of waters for life. Iron, an important nutrient, is relatively insoluble, and metal–ligand complexes are required to keep the iron in solution and bioavailable. Sunlight often degrades these metal–ligand complexes, and the subsequently released iron can outcompete other (trace) metals for their ligands. A ‘domino’ effect on weaker metal–ligand complexes will occur which complicates the actual dynamic speciation and its measurements. Abstract. The effect of photodegradation of iron(iii)-EDTA on the chemical speciation of both iron and cobalt has been tested both in a simple medium and in a more complex algal growth medium. In both media, the photodegradation of iron(iii)-EDTA caused iron(iii) to be released as a free ionic species. Released iron(iii) could be modelled as engaged in precipitation and in competition with cobalt, initially also bound to EDTA. Cobalt appeared as free ionic species after a certain lag. The length of this lag phase was proportional to the amount of EDTA added to the media, which indicated that the surplus of EDTA was first targetted by iron(iii)-EDTA photodegradation, after which iron(iii) out-competed cobalt for the EDTA in the metal–EDTA pool. All data were fitted, using a model on speciation kinetics for cobalt-EDTA and iron(iii)-EDTA, taking into account photodegradation rates of iron(iii)-EDTA and precipitation of free iron(iii). The modelled rate of iron(iii)-EDTA photodegradation was compared to direct HPLC measurements of the disappearance of iron(iii)-EDTA due to photodegradation, the latter, however, with a different iron(iii)-EDTA concentration regime. The results suggest that photodegradation is a complex process which is greatly influenced by experimental conditions (e.g. light intensity/spectrum, iron(iii), and EDTA concentrations). Iron(iii)-desferrioxamine B (DFO-B) was suggested as a possible alternative for EDTA in experimental media: photostability was shown for prolonged experimental periods.

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Linsler, Dominic, Friederike Ruebeling et Christian Greiner. « Subsurface Microstructural Evolution during Scratch Testing on Bcc Iron ». Metals 11, n^o 8 (10 août 2021) : 1258. http://dx.doi.org/10.3390/met11081258.

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Subsurface microstructures influence the friction and wear behavior of metallic tribological systems, among other factors. To gain a basic understanding of the microstructural changes occurring during sliding processes, face-centered cubic model systems, for example a copper system with a sapphire sphere sliding against it, were previously characterized. Such systems showed the evolution of the dislocation self-organization phenomenon called the dislocation trace line. To test the occurrence of this dislocation arrangement in bcc metals, in this study a ruby ball was slid against electropolished bcc iron under an increasing normal load. The wear track topography and subsurface microstructure were characterized using white light interferometry and scanning transmission electron microscopy. The analysis suggested that at least for bcc iron, the evolution of a dislocation trace line is connected with the onset of pronounced plastic deformation.

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Vargas-González, Héctor Hugo, Jose Alfredo Arreola Lizárraga, Lia Mendez-Rodriguez, Ramon Gaxiola Robles, Jaqueline Garcia Hernández et Sergio Ticul Alvarez Castañeda. « Effect of aquaculture-agriculture sewage on the relation between iron and other trace elements content in Venus clam ». Maritime Technology and Research 2, n^o 4 (28 mai 2020) : Manuscript. http://dx.doi.org/10.33175/mtr.2020.241229.

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In coastal systems, concentrations of trace metals in filter feeders such as shellfish may be affected by anthropogenic activities, including agriculture and aquaculture. Shellfish are a good source of iron, but can also be a potential source of toxic elements, such as cadmium and lead, when consumed by humans. The objective of this study was to determine the differences in iron, zinc, copper, manganese, nickel, lead, and cadmium levels in tissue of the clam Chione gnidia collected from a coastal lagoon influenced by agriculture (Lobos) or aquaculture (Tobari), using an atomic absorption spectrophotometer. The relationship of iron with all other trace elements in these organisms was explored using a generalized linear model (GLM). Iron, copper, manganese, and cadmium concentrations were significantly higher in shellfish collected from the coastal lagoon influenced by agriculture, while nickel was significantly higher in shellfish from the lagoon influenced by aquaculture. In these shellfish, cadmium and lead levels were the factors limiting the weekly intake of clam flesh. The GLM model explained 59% of the iron concentration in the Venus clam, suggesting that this element is directly related to zinc and manganese levels, but inversely related to cadmium content in shellfish.

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Martínez López, Salvadora, Ascensión Banegas García, Carmen Pérez Sirvent, Maria José Martínez Sánchez et Maria Angeles Esteban Abad. « The Arsenic Biogeochemical Cycle : A Review ». Advances in Environmental and Engineering Research 04, n^o 04 (23 novembre 2023) : 1–26. http://dx.doi.org/10.21926/aeer.2304051.

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This paper reviews the arsenic in the environment. Arsenic contamination is currently one of the leading environmental problems worldwide. The arsenic (As) cycle is the subject of this article because As is an element with a significant impact on living beings and because of its interrelation with other biogeochemical cycles. The biogeochemical cycle of As is closed, so this trace element returns to sediments where it can be changed in its chemical state by micro-organisms present in soils. In addition, some minerals contribute to the sequestration and retention of As. This element interferes with other critical biogeochemical cycles such as sulfur, phosphorus, iron, manganese, and antimony. Another factor to consider is determining the content and interference of organic matter in the soil, as it forms very stable compounds with As. On the other hand, in aquatic environmental conditions, with a high concentration of organic matter and anaerobiosis, a reducing environment is created that facilitates the mobilization of As in the sediments.

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Lešková, Alexandra, Hélène Javot et Ricardo F. H. Giehl. « Metal crossroads in plants : modulation of nutrient acquisition and root development by essential trace metals ». Journal of Experimental Botany 73, n^o 6 (16 novembre 2021) : 1751–65. http://dx.doi.org/10.1093/jxb/erab483.

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Abstract The metals iron, zinc, manganese, copper, molybdenum, and nickel are essential for the growth and development of virtually all plant species. Although these elements are required at relatively low amounts, natural factors and anthropogenic activities can significantly affect their availability in soils, inducing deficiencies or toxicities in plants. Because essential trace metals can shape root systems and interfere with the uptake and signaling mechanisms of other nutrients, the non-optimal availability of any of them can induce multi-element changes in plants. Interference by one essential trace metal with the acquisition of another metal or a non-metal nutrient can occur prior to or during root uptake. Essential trace metals can also indirectly impact the plant’s ability to capture soil nutrients by targeting distinct root developmental programs and hormone-related processes, consequently inducing largely metal-specific changes in root systems. The presence of metal binding domains in many regulatory proteins also enables essential trace metals to coordinate nutrient uptake by acting at high levels in hierarchical signaling cascades. Here, we summarize the known molecular and cellular mechanisms underlying trace metal-dependent modulation of nutrient acquisition and root development, and highlight the importance of considering multi-element interactions to breed crops better adapted to non-optimal trace metal availabilities.

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Strzelec, Michal, Bernadette C. Proemse, Melanie Gault-Ringold, Philip W. Boyd, Morgane M. G. Perron, Robyn Schofield, Robert G. Ryan et al. « Atmospheric Trace Metal Deposition near the Great Barrier Reef, Australia ». Atmosphere 11, n^o 4 (15 avril 2020) : 390. http://dx.doi.org/10.3390/atmos11040390.

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Aerosols deposited into the Great Barrier Reef (GBR) contain iron (Fe) and other trace metals, which may act as micronutrients or as toxins to this sensitive marine ecosystem. In this paper, we quantified the atmospheric deposition of Fe and investigated aerosol sources in Mission Beach (Queensland) next to the GBR. Leaching experiments were applied to distinguish pools of Fe with regard to its solubility. The labile Fe concentration in aerosols was 2.3–10.6 ng m−3, which is equivalent to 4.9%–11.4% of total Fe and was linked to combustion and biomass burning processes, while total Fe was dominated by crustal sources. A one-day precipitation event provided more soluble iron than the average dry deposition flux, 0.165 and 0.143 μmol m−2 day−1, respectively. Scanning Electron Microscopy indicated that alumina-silicates were the main carriers of total Fe and samples affected by combustion emissions were accompanied by regular round-shaped carbonaceous particulates. Collected aerosols contained significant amounts of Cd, Co, Cu, Mo, Mn, Pb, V, and Zn, which were mostly (47.5%–96.7%) in the labile form. In this study, we provide the first field data on the atmospheric delivery of Fe and other trace metals to the GBR and propose that this is an important delivery mechanism to this region.

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Ndinwa, G. C. C., M. Peretomode et T. Asiagbe. « Distribution of Trace Metals in Vertebrate and Invertebrate Species from Ubeji Creek, Southern Nigeria ». International Journal of Advances in Life Science and Technology 1, n^o 1 (16 juin 2014) : 16–24. http://dx.doi.org/10.18488/journal.72/2014.1.1/72.1.16.24.

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Trace metals content in water, fishes (Tilapia mariae, Clarias gariepinus), earthworm (Libydrius violaceous) and sediment were determined from Ubeji River using Atomic Absorption Spectrophotometer (AAS). Metals determined were lead, cadmium, zinc, mercury, arsenic, copper and Iron. The results obtained revealed that all the metals were detected. Also, there were variations in metal levels in the samples. Highest Zn level was obtained in all the samples analysed (0.284ppm and 0.284ppm in water, 24.0mg/kg in Clarias gariepinus, 28.8mg/kg in Tilapia mariae, 1.16mg/kg in earthworm and 0.64mg/kg in sediment). The concentrations of trace metals obtained in this study are found to be dangerous. The metal levels in water from Ubeji River are higher than the WHO/FEPA standards for water quality. The concentrations of lead, zinc and copper obtained in the whole body of fishes exceeded the WHO/FEPA set standards for aquatic life. The presence of trace metals found in the sample from Ubeji River is attributed to the proximity of petroleum activity, construction works and other allied companies.

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Coleman, Margaret E., Robert S. Elder, Parthaprattim Basu et Gary P. Koppenaal. « Trace Metals in Edible Tissues of Livestock and Poultry ». Journal of AOAC INTERNATIONAL 75, n^o 4 (1 juillet 1992) : 615–25. http://dx.doi.org/10.1093/jaoac/75.4.615.

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Abstract Data from a random-sampling study are presented for trace metals in edible tissues of livestock (bovine including bull, steer, cow, heifer, calf; ovine including mature sheep and lambs; porcine including market hogs, boar/stag, and sow) and poultry (including young and mature chicken, young turkey, and duck). Tissue homogenates were ashed, and residual materials were dissolved in hydrochloric acid for analysis by atomic absorption spectroscopy. Statistical summaries of data are provided for the trace metals lead, cadmium, cobalt, copper, iron, manganese, nickel, and zinc. The heavy metals of toxicological concern, lead and cadmium, are emphasized in this study. Lead and cadmium were rarely detected in muscle (0.2-0.5% positive among 2314 animals sampled). Lead was also infrequently detected in liver (1.8% positive) and kidney (2.4% positive). Nearly 46% of livers analyzed were positive for cadmium, and approximately 78% of kidney samples were positive for cadmium. No regulatory limits are established in the United States for the trace metals reported in this study, although restrictions on the use of kidneys from mature poultry as human food have been established because of concern about potential cadmium levels. Kidneys from this study, more frequently than livers, bore cadmium levels that exceeded the regulatory limits of other countries or organizations. Regulatory implications of the data are discussed.

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Al-Yaseri, S. T. L. « Assessment of the accumulation of some trace metals in whole body of fresh water shrimp Atyaephyra desmaresti mesopotamica from Shatt Al-Arab River, Basrah, Iraq ». Mesopotamian Journal of Marine Sciences 25, n^o 2 (27 avril 2022) : 146–53. http://dx.doi.org/10.58629/mjms.v25i2.200.

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Concentrations of heavy metals (Pb, Mn, Ni, Fe, Cu, and Zn) were determined in shrimp Atyaephyra desmaresti mesopotamica collected from Shatt Al-Arab River, Basrah, Iraq. The elements content were determined in whole body biomass. The seasonal variations of the element concentrations, and the relationship between element concentrations in males and females were estimated in this study. Measurements were done to evaluate trace metals in shrimps tissues in Qurmat-Ali in Shatt Al-Arab River between summer (May- August) 2008 and spring (March and April) 2009. Samples were collected seasonally. Tissue samples were analyzed by flame atomic absorption spectrophotometry. Females accumulated the trace metals in their bodies in spring higher than other seasons. Males accumulated the trace metals in their bodies in Spring higher than other seasons, except for Pb and Mn. Regarding to concentrations; the highest values were 141.80 µg g-1 d.w in males and 136.79 µg g-1 d.w in females for Iron, while the lowest values were 2.49 µg g-1 d.w in males and 2.96 µg g-1 d.w in females for Lead. Regarding to seasons; in Summer the concentrations of trace metals were higher in males than in females, except Zn, in Autumn they were higher in males than in females, except Pb and Ni, in Winter they were higher in males than in females, except Pb and Zn, in Spring they were higher in males than in females, except Pb, Mn and Zn.

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Tyczyńska, Magdalena, Marta Gędek, Adam Brachet, Wojciech Stręk, Jolanta Flieger, Grzegorz Teresiński et Jacek Baj. « Trace Elements in Alzheimer’s Disease and Dementia : The Current State of Knowledge ». Journal of Clinical Medicine 13, n^o 8 (19 avril 2024) : 2381. http://dx.doi.org/10.3390/jcm13082381.

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Changes in trace element concentrations are being wildly considered when it comes to neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease. This study aims to present the role that trace elements play in the central nervous system. Moreover, we reviewed the mechanisms involved in their neurotoxicity. Low zinc concentrations, as well as high levels of copper, manganese, and iron, activate the signalling pathways of the inflammatory, oxidative and nitrosative stress response. Neurodegeneration occurs due to the association between metals and proteins, which is then followed by aggregate formation, mitochondrial disorder, and, ultimately, cell death. In Alzheimer’s disease, low Zn levels suppress the neurotoxicity induced by β-amyloid through the selective precipitation of aggregation intermediates. High concentrations of copper, iron and manganese cause the aggregation of intracellular α-synuclein, which results in synaptic dysfunction and axonal transport disruption. Parkinson’s disease is caused by the accumulation of Fe in the midbrain dopaminergic nucleus, and the pathogenesis of multiple sclerosis derives from Zn deficiency, leading to an imbalance between T cell functions. Aluminium disturbs the homeostasis of other metals through a rise in the production of oxygen reactive forms, which then leads to cellular death. Selenium, in association with iron, plays a distinct role in the process of ferroptosis. Outlining the influence that metals have on oxidoreduction processes is crucial to recognising the pathophysiology of neurodegenerative diseases and may provide possible new methods for both their avoidance and therapy.

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OKADA, Yukiko, et Shoji HIRAI. « Determination of Trace Tramp Elements and Other Trace Elements in Pure Iron Standard Materials by Instrumental Neutron Activation Analysis ». Tetsu-to-Hagane 89, n^o 9 (2003) : 900–905. http://dx.doi.org/10.2355/tetsutohagane1955.89.9_900.

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Dexter, David T., Peter Jenner, Anthony H. V. Schapira et C. David Marsden. « Alterations in levels of iron, ferritin, and other trace metals in neurodegenerative diseases affecting the basal ganglia ». Annals of Neurology 32, S1 (1992) : S94—S100. http://dx.doi.org/10.1002/ana.410320716.

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Podgórski, Tomasz, Jakub Kryściak, Jan Konarski, Katarzyna Domaszewska, Krzysztof Durkalec-Michalski, Ryszard Strzelczyk et Maciej Pawlak. « Iron Metabolism in Field Hockey Players During an Annual Training Cycle ». Journal of Human Kinetics 47, n^o 1 (1 septembre 2015) : 107–14. http://dx.doi.org/10.1515/hukin-2015-0066.

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AbstractPost-physical training changes in iron metabolism in the human body often occur. To fully describe these processes, fifteen male Polish National Team field hockey players (age 27.7 ± 5.2 years, body mass 72.8 ± 7.6 kg and body height 177.1 ± 5.7 cm) were examined in three phases of an annual training cycle: preparatory (T1), competitive (T2) and transition (T3). To assess aerobic fitness, maximal oxygen uptake (VO2max) was evaluated. Based on the iron concentration, the changes in total iron binding capacity (TIBC), unsaturated iron binding capacity (UIBC) and other selected haematological indicators (haemoglobin, erythrocytes, mean corpuscular haemoglobin - MCH) in iron metabolism were estimated. The average values of maximum oxygen uptake increased from 54.97 ± 3.62 ml·kg−1·min−1in T1 to 59.93 ± 3.55 ml·kg−1·min−1in T2 (p<0.05) and then decreased to 56.21 ± 4.56 ml·kg−1·min−1in T3 (p<0.05). No statistically significant changes in the erythrocyte count were noted. The MCH and haemoglobin concentration decreased between T1 and T2. The maximal exercise test caused a significant (p<0.05) increase in the plasma iron concentration during the competition and transition phases. Progressive but non-significant increases in resting iron concentration, TIBC and UIBC in the analysed annual training cycle were noted. To show global changes in iron metabolism in the human body, it is necessary to determine additional variables, i.e. UIBC, TIBC, haemoglobin, MCH or the erythrocyte count. The direction of changes in iron metabolism depends on both the duration and intensity of the physical activity and the fitness level of the subjects. Dietary intake of iron increases the level of this trace element and prevents anaemia associated with training overloads.

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Hisira, Vladimír, Marián Kadaši, Róbert Klein, Lýdia Mesarčová et Ján Pošivák. « Bioaccumulation of Cu, Fe and Zn in Wild Ruminants in Middle Gemer Region ». Chemické listy 116, n^o 9 (15 septembre 2022) : 543–47. http://dx.doi.org/10.54779/chl20220543.

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The aim of this study was to monitor trace metals (copper, iron and zinc) concentrations in parenchymatous organs and muscle tissue of red deer (n=23) and roe deer (n=25) that were hunted down in the middle Gemer region in south central Slovakia. Being expressed in mg kg–1 in all cases, these concentrations assumed the following values: mean renal copper concentration in red deer was 4.36, hepatic 19.65, muscle 1.96; renal iron concentration was 72.5, hepatic 131.9, muscle 45.09; mean zinc concentration in kidney was 27.77, in liver 30.22 and in muscle 29.58 , respectively. In roe deer, mean level of copper in kidney was 4.83, in the liver 26.4, in muscle tissue 2.1; mean concentration of iron in kidney was 66.69, in liver 122.83, in muscle tissue 49.07; mean concentration of zinc in kidney was 27.34, in liver 29.76, and in muscle tissue 24.37, respectively. Concentration of metals under study in different age groups showed that the values rose proportionally with age except for zinc concentration, where the highest Zn concentrations were detected in muscle of young animals. In other trace metal levels no significant differences were detected between age groups, males or females. Based on the given results, the Revuca district does not show itself as the most polluted region considering surveyed heavy metals, but nevertheless the presented results document that the presence of heavy metals in the tissues of game is still an interesting object for the next studies.

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Mizhir, Alaa A., Wesal F. Hassan, Dounia K. K. Al-Khuzie et Zuhair A. Abdulnabi. « Use of sequential extraction methods to evaluate the environmental impact of trace metal in the Iraqi coastlines ». Basrah Journal of Agricultural Sciences 36, n^o 2 (27 décembre 2023) : 17–29. http://dx.doi.org/10.37077/25200860.2023.36.2.02.

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The geochemical distribution of several trace metals (lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), nickel (Ni), chrome (Cr), cobalt (Co) and iron (Fe)) was investigated using five sequential extraction procedures to provide information on their distribution and environmental impacts on the Iraqi coastal sediments. Sediment samples were collected from 16 sites along the coast to determine the concentrations of the above metals. The concentration and ratios of these metals were estimated in the sediment extract (concentration on the exchange surfaces, carbonates, manganese oxides and iron oxides, organic matter and those associated with the remainder) using extraction methods (magnesium chloride, 1 molar of sodium acetate, 0.5 molar of hydroxylamine hydrochloride, 0.2 molar of ammonium oxalate, concentrated nitric acid and 25% of hydrofluoric acid) to extract and separate the above fractions in order. The results indicated that the total sediment content of Pb and Cd were higher than their rate of occurrence in the crust, while copper, zinc, nickel, chrome, cobalt and iron were within those limits. According to the I-geo the metals Cr, Cu and Zn are considered at unpolluted class while Ni and Pb were ranged from moderately to strongly level. On the other had Cd was found at extremely level as its I-geo exceeded the highest-class value. These metals are bonded to different power bonds. Pb, Cr and Co have dominant in exchangeable and carbonates fraction. Iraqi tidal flats is characterized by very high risk considering Cr, Pb, Co and Cu which represented by RAC values, so they can move to the solution to become available for living.

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Kawahara, Masahiro, Midori Kato-Negishi et Ken-ichiro Tanaka. « Neurometals in the Pathogenesis of Prion Diseases ». International Journal of Molecular Sciences 22, n^o 3 (28 janvier 2021) : 1267. http://dx.doi.org/10.3390/ijms22031267.

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Prion diseases are progressive and transmissive neurodegenerative diseases. The conformational conversion of normal cellular prion protein (PrPC) into abnormal pathogenic prion protein (PrPSc) is critical for its infection and pathogenesis. PrPC possesses the ability to bind to various neurometals, including copper, zinc, iron, and manganese. Moreover, increasing evidence suggests that PrPC plays essential roles in the maintenance of homeostasis of these neurometals in the synapse. In addition, trace metals are critical determinants of the conformational change and toxicity of PrPC. Here, we review our studies and other new findings that inform the current understanding of the links between trace elements and physiological functions of PrPC and the neurotoxicity of PrPSc.

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ISINKARALAR, KAAN. « Some atmospheric trace metals deposition in selected trees as a possible biomonitor ». Romanian Biotechnological Letters 27, n^o 1/2022 (10 janvier 2022) : 3225–34. http://dx.doi.org/10.25083/rbl/27.1/3225-3234.

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Several trees are effectively used to biomonitor of trace metals in urban environmental pollution. It gives information about the speciation of trace metals and their transition between organs in the plant. In the wood of the trees, it can be determined which part is formed in which year with the help of organs formed by the effect of seasonal differences. Air pollutants damage to humans and other living things in nature is generally referred to as a sign of pollution. They are released from anthropogenic sources accumulate in the bodies of nearby species over time. They give information about the history of air pollutants due to the accumulation in their wood, inner bark, and outer bark. In this study, organs of Robinia pseudoacacia L., Cupressus arizonica G., and Platanus orientalis L. were analyzed as biomonitors with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). All samples were taken from Kocaeli province industrial zone which has quite a wide industrial area. The concentration of selected trace elements as Iron (Fe), Magnesium (Mg), and Zinc (Zn) their emission caused by industrial activities and transport vehicle density. The results of the study show that Robinia pseudoacacia L. was the most suitable species for Fe, Mg, and Zn concentration levels as a biomonitor.

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Igweze, Zelinjo Nkiruka, Osazuwa Clinton Ekhator, Ify Nwaogazie, Chiara Frazzoli et Orish Ebere Orisakwe. « Appropriateness of Essentials Trace Metals in Commonly Consumed Infant Formulae in Nigeria ». Open Access Macedonian Journal of Medical Sciences 7, n^o 23 (11 décembre 2019) : 4168–75. http://dx.doi.org/10.3889/oamjms.2019.706.

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BACKGROUND: Mothers who feed their children with infant food have increased have over the years leaving a large percentage of children who consume other types of liquid food for supplementation or as alternatives. AIM: Determining the levels of essential trace metals in these formulae with the aim of ascertain their appropriateness is considered important. METHODS: Iron, zinc, manganese, chromium and cobalt in 26 infant formulae purchased from Port Harcourt city, Nigeria were determined by Atomic Absorption Spectrophotometry. The estimated daily intake EDI and percentage of EDI to the recommended daily allowance of these essential trace metals were used in the exposure assessment. RESULTS: The highest mean concentration of Mn, Cr and Co was found in the milk based (0.15 ± 0.09 mg/kg), (0.61 ± 0.70 mg/kg), (0.12 ± 0.32 mg/kg) compared to the cereal based and cereal mix based but the differences was also not significant. The EDI of chromium in the infant formulae exceeded the RDA. CONCLUSION: Infant formulae may add to the chromium body burden of infants in Nigeria.

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Berroukeche, Farid, Nassima Mokhtari-Soulimane, Asmahan Imessaoudene, Ahmed Sabri Cherrak, Pascale Ronot, Anne Boos, Amina Belhandouz, Hafida Merzouk et Mourad Elhabiri. « Oral Supplementation Effect of Iron and its Complex Form With Quercetin on Oxidant Status and on Redistribution of Essential Metals in Organs of Streptozotocin Diabetic Rats ». Romanian Journal of Diabetes Nutrition and Metabolic Diseases 26, n^o 1 (1 mars 2019) : 39–53. http://dx.doi.org/10.2478/rjdnmd-2019-0005.

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Abstract Background and aims: Quercetin, is a polyphenolic antioxidant compound. It is able to form complex with metal ions such as iron and exerts a broad range of biological activities like improving metabolic disorders. This research aims at investigating the effect of oral supplementation of iron (2.5mg Fe/Kg/day) and its complex form (molar ratio 1:5; 2.5mg/25mg/Kg/day) with quercetin (25mg/Kg/day) on lipid metabolism, oxidant status and trace elements contents in organs of Wistar diabetic rats (45 mg/kg/rat.ip of streptozotocin) during eight weeks of experimentation. Material and method: To achieve this, liver and adipose tissue enzymes activities, NO•, O2−•, TBARs, carbonyl protein levels in plasma were analysed. Metals (Cu, Fe, Mg, Zn) analysis of organs were determined by inductively coupled plasma atomic emission spectroscopy. Results: Iron supplemented alone induced a noticeable disorder in lipid, lipoprotein, lipases and oxidant status. Yet, it caused an imbalance in the redistribution of metals in the organs of diabetic and non diabetic rats. Iron-quercetin complex was shown as less harmful and more beneficial than iron supplemented alone. Conclusions: This complex could reverse oxidative stress and iron deficiency mostly caused by the diabetic disease but at the same time it induces an imbalance in redistribution of other essential metals.

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Antcibor, I., A. Eschenbach, S. Zubrzycki, L. Kutzbach, D. Bolshiyanov et E. M. Pfeiffer. « Trace metal distribution in pristine permafrost-affected soils of the Lena River delta and its hinterland, northern Siberia, Russia ». Biogeosciences 11, n^o 1 (2 janvier 2014) : 1–15. http://dx.doi.org/10.5194/bg-11-1-2014.

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Abstract. Soils are an important compartment of ecosystems and have the ability to buffer and immobilize substances of natural and anthropogenic origin to prevent their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since Arctic ecosystems are considered to be highly sensitive to climatic changes as well as to chemical contamination. This study characterises background levels of trace metals in permafrost-affected soils of the Lena River delta and its hinterland in northern Siberia (73.5–69.5° N), representing a remote region far from evident anthropogenic trace metal sources. Investigations on the element content of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co), and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest median concentrations of Fe and Mn were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) while the highest median values of Ni, Pb and Zn were found in soils of both the ice-complex and the Holocene estuarine terrace of the Lena River delta region, as well as in the southernmost study unit of the hinterland area. Detailed observations of trace metal distribution on the micro scale showed that organic matter content, soil texture and iron-oxide contents influenced by cryogenic processes, temperature, and hydrological regimes are the most important factors determining the metal abundance in permafrost-affected soils. The observed range of trace element background concentrations was similar to trace metal levels reported for other pristine northern areas.

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Greenwald, Jason, Gabrielle Zeder-Lutz, Agnès Hagege, Hervé Celia et Franc Pattus. « The Metal Dependence of Pyoverdine Interactions with Its Outer Membrane Receptor FpvA ». Journal of Bacteriology 190, n^o 20 (18 juillet 2008) : 6548–58. http://dx.doi.org/10.1128/jb.00784-08.

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ABSTRACT To acquire iron, Pseudomonas aeruginosa secretes the fluorescent siderophore pyoverdine (Pvd), which chelates iron and shuttles it into the cells via the specific outer membrane transporter FpvA. We studied the role of iron and other metals in the binding and transport of Pvd by FpvA and conclude that there is no significant affinity between FpvA and metal-free Pvd. We found that the fluorescent in vivo complex of iron-free FpvA-Pvd is in fact a complex with aluminum (FpvA-Pvd-Al) formed from trace aluminum in the growth medium. When Pseudomonas aeruginosa was cultured in a medium that had been treated with a metal affinity resin, the in vivo formation of the FpvA-Pvd complex and the recycling of Pvd on FpvA were nearly abolished. The accumulation of Pvd in the periplasm of Pseudomonas aeruginosa was also reduced in the treated growth medium, while the addition of 1 μM AlCl3 to the treated medium restored the effects of trace metals observed in standard growth medium. Using fluorescent resonance energy transfer and surface plasmon resonance techniques, the in vitro interactions between Pvd and detergent-solubilized FpvA were also shown to be metal dependent. We demonstrated that FpvA binds Pvd-Fe but not Pvd and that Pvd did not compete with Pvd-Fe for FpvA binding. In light of our finding that the Pvd-Al complex is transported across the outer membrane of Pseudomonas aeruginosa, a model for siderophore recognition based on a metal-induced conformation followed by redox selectivity for iron is discussed.

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Antcibor, I., S. Zubrzycki, A. Eschenbach, L. Kutzbach, D. Bol'shiyanov et E. M. Pfeiffer. « Trace metal distribution in pristine permafrost-affected soils of the Lena River Delta and its Hinterland, Northern Siberia, Russia ». Biogeosciences Discussions 10, n^o 2 (6 février 2013) : 2205–44. http://dx.doi.org/10.5194/bgd-10-2205-2013.

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Abstract. Soils are an important compartment of ecosystems and have the ability to immobilize chemicals preventing their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since the Arctic ecosystems are considered to be very sensitive to climatic changes as well as to chemical contamination. This study characterizes background levels of trace metals in permafrost-affected soils of the Lena River Delta and its hinterland in northern Siberia (73.5° N–69.5° N) representing a remote region far from evident anthropogenic trace metal sources. Investigations on total element contents of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co) and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest concentrations of the majority of the measured elements were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) in the Lena River Delta region. Correlation analyses of trace metal concentrations and soil chemical and physical properties at a Holocene estuarine terrace and two modern floodplain levels in the southern-central Lena River Delta (Samoylov Island) showed that the main factors controlling the trace metal distribution in these soils are organic matter content, soil texture and contents of iron and manganese-oxides. Principal Component Analysis (PCA) revealed that soil oxides play a significant role in trace metal distribution in both top and bottom horizons. Occurrence of organic matter contributes to Cd binding in top soils and Cu binding in bottom horizons. Observed ranges of the background concentrations of the majority of trace elements were similar to background levels reported for other pristine arctic areas and did not exceed mean global background concentrations examined for the continental crust as well as for the world's soils.

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DEXTER, D. T., A. CARAYON, F. JAVOY-AGID, Y. AGID, F. R. WELLS, S. E. DANIEL, A. J. LEES, P. JENNER et C. D. MARSDEN. « ALTERATIONS IN THE LEVELS OF IRON, FERRITIN AND OTHER TRACE METALS IN PARKINSON'S DISEASE AND OTHER NEURODEGENERATIVE DISEASES AFFECTING THE BASAL GANGLIA ». Brain 114, n^o 4 (1991) : 1953–75. http://dx.doi.org/10.1093/brain/114.4.1953.

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Saeed, Adel A., et Galal K. Sheikh. « Elemental Analysis of Some Heavy Metals in Hijamah and Venous Blood Samples ». Yemeni Journal of Medical and Health Research 12, n^o 2 (1 février 2023) : 79–88. http://dx.doi.org/10.47372/yjmhr.2023(12).2.2.

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Introduction: Hijamah as one famous therapeutic method used in traditional and new medicine can be done by special cups for sucking blood in wet and dry cupping therapy. The excessive use of minerals in various fields of life has become a threat to human health as they can accumulate in the body and lead to several chronic diseases. Objective: This study was done to know the ability of wet hijamah on ridding the body of trace minerals and comparing the concentration of investigated elements with that found in venous blood samples. Methods: The blood samples were collected from 18 volunteers. The samples were digested at ~65 ⁰C using a mixture of nitric acid and hydrogen peroxide in a ratio of (2:1), and then an inductively coupled plasma - optical emission spectrometry (ICP-OES) was used to determine the concentration of trace elements iron (Fe), nickel (Ni), chromium (Cr), cobalt (Co), cadmium (Cd), zinc (Zn), aluminum (Al), copper (Cu) and lead (Pb). Relationships between the studied blood samples were examined using SPSS statistical software. Results: It was noted that some trace elements in hijamah and venous had statistically significant differences were Fe, Ni, Cd, Zn, Al, Cu, and Pb, where the values of p (< 0.0001, 0.046, 0.024, 0.005, 0.009, 0.024, and 0.012 respectively). While the other elements did not show statistically significant differences, namely, Cr and Co, at p 0.263, and 0.416, respectively. Conclusion: The study showed that wet hijamah can be safely applied to reduce the levels of trace elements in the blood. It may be useful for people who work in jobs where the accumulation of toxic elements in their bodies is possible.

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Yiu, Stephanie, Kwai Hui, Chung Choi, Richard Kao, Chi Ma, Dan Yang et Alan Chiang. « Intracellular Iron Chelation by a Novel Compound, C7, Reactivates Epstein–Barr Virus (EBV) Lytic Cycle via the ERK-Autophagy Axis in EBV-Positive Epithelial Cancers ». Cancers 10, n^o 12 (11 décembre 2018) : 505. http://dx.doi.org/10.3390/cancers10120505.

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Pharmaceutical reactivation of lytic cycle of Epstein–Barr virus (EBV) represents a potential therapeutic strategy against EBV-associated epithelial malignancies, e.g., gastric carcinoma (GC) and nasopharyngeal carcinoma (NPC). A novel lytic-inducing compound, C7, which exhibits structural similarity to Di-2-Pyridyl Ketone 4, 4-Dimethyl-3-Thiosemicarbazone (Dp44mT), a known chelator of intracellular iron, is found to reactivate EBV lytic cycle in GC and NPC. This study aims to investigate the role of intracellular iron chelation by C7 and other iron chelators in lytic reactivation of EBV in GC and NPC. Testing of six structural analogs of C7 revealed only those which have high affinity towards transition metals could induce EBV lytic cycle. Precomplexing C7 and iron chelators to iron prior to treatment of the cells abolished EBV lytic reactivation. Though hypoxia signaling pathway was activated, it was not the only pathway associated with EBV reactivation. Specifically, C7 and iron chelators initiated autophagy by activating extracellular signal-regulated kinase (ERK1/2) to reactivate EBV lytic cycle since autophagy and EBV lytic reactivation were abolished in cells treated with ERK1/2 blockers whilst inhibition of autophagy by 3-Methyladenine (3-MA) and atg5 knockdown significantly abolished EBV lytic reactivation. In summary, we discovered a novel mechanism of reactivation of the EBV lytic cycle through intracellular iron chelation and induction of ERK-autophagy axis in EBV-positive epithelial malignancies, raising the question whether clinically available iron chelators can be incorporated into existing therapeutic regimens to treat these cancers.

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Kulikova, M. S., A. V. Shishkin et A. N. Kulikov. « THE CONTENT OF TRACE ELEMENTS IN THE BLOOD OF CALVES THAT RECEIVED FEED ADDITIVES BASED ON THEIR CHELATED COMPLEX COMPOUNDS AND INORGANIC SALTS ». Scientific Notes Kazan Bauman State Academy of Veterinary Medicine 247, n^o 3 (5 septembre 2021) : 108–12. http://dx.doi.org/10.31588/2413-4201-1883-247-3-108-112.

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We have proposed liquid feed additives, which are solutions of substances that can react with each other to form complex compounds of different composition. The dynamic equilibrium is established in the solution. If the pH changes and one complex compound decomposes, a new one is formed immediately. As a result, the trace element metal ions are chelated at a very wide range of pH values. The effectiveness of the use of solutions of chelated complex compounds and solutions of inorganic salts of copper, zinc, iron, cobalt and manganese was compared. These fluids were administered orally to two experimental groups of calves for 30 days according to a fractional-periodic scheme. Another (control) group received distilled water. The content of these trace elements in the blood of animals was evaluated. The fractional-periodic scheme of administration was used to reduce the influence of physiological antagonism and synergy of trace elements on the results of the experiment. It was shown that in calves from the experimental groups, the content of copper, zinc, iron, cobalt and manganese in the blood was significantly higher than in the control group. At the same time, calves that received solutions of complex compounds of metals-trace elements had a higher content in their blood compared to animals that received solutions of inorganic salts.

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Rivaro, Paola, Francisco Ardini, Davide Vivado, Roberto Cabella, Pasquale Castagno, Olga Mangoni et Pierpaolo Falco. « Potential Sources of Particulate Iron in Surface and Deep Waters of the Terra Nova Bay (Ross Sea, Antarctica) ». Water 12, n^o 12 (14 décembre 2020) : 3517. http://dx.doi.org/10.3390/w12123517.

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The distribution of particulate Fe (pFe), suspended particulate matter (SPM), and other particulate trace metals were investigated in Terra Nova Bay as part of CDW Effects on glaciaL mElting and on Bulk of Fe in the Western Ross sea (CELEBeR) and Plankton biodiversity and functioning of the Ross Sea ecosystems in a changing Southern Ocean (P-ROSE) projects. Variable concentrations of SPM (0.09–97 mg L−1), pFe (0.51–8.70 nM) and other trace metals were found in the Antarctic Surface waters (AASW) layer, where the addition of meltwater contributed to the pool with both lithogenic and biogenic forms. The deeper layer of the water column was occupied by High Salinity Shelf Water (HSSW) and Terra Nova Bay Ice Shelf Water (TISW) encompassing glacial water as confirmed by the lightest δ18O measured values. The concentration of pFe in TISW (11.7 ± 9.2 nM) was higher than in HSSW samples (5.55 ± 4.43 nM), suggesting that the drainage of material released from glaciers surrounding the area is relevant in terms of pFe contribution. Particulate Fe/Al and Mn/Al ratios were substantially in excess compared with the mean crustal ratios. Microscopic analyses confirmed that more labile Fe oxyhydroxides and authigenic MnO2 phases were present together with biogenic sinking material. Future expected increasing melt rates of these glaciers enlarge Fe input, thus having a greater role in supplying iron and counteracting the reductions in sea ice cover around Terra Nova Bay.

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Lima, L. S., U. C. Oliveira, C. M. A. Rangel, C. F. Barreto, V. M. C. Aguiar, J. A. Baptista Neto et E. M. Fonseca. « Assessment of Pollutants in Soils and Groundwater from the Coastal Plain of Paraíba do Sul River Delta, RJ, Brazil ». Revista de Gestão Costeira Integrada 20, n^o 4 (décembre 2020) : 219–31. http://dx.doi.org/10.5894/rgci-n159.

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In developing countries, the quality of the available freshwater is deteriorating mainly due to pollution. Underground water bodies are important resources, taking into account that they are usually more isolated and also protected from anthropogenic influence. Within this context, the present study aimed to assess trace metals, nitrate and organic contaminants in groundwater and soils from 10 bore wells located at the coastal plain of the Paraíba do Sul river delta. Groundwater of the study area revealed elevated concentrations of arsenic, iron, manganese and barium, surpassing the limits established by Brazilian legislation as well as the limits established by other regulatory agencies. As, Fe and Ba reached concentrations as high as 242.70, 31 919 and 4.041 µg.l-1 in groundwater. Despite the elevated values, results suggested a reducing environment and the contaminants appear to have a natural geogenic origin, which is corroborated by past studies in the same area. Soils of the aquifer presented low levels of trace metals, corroborating the hypothesis of geogenic contamination in groundwater. No significant differences among the bore wells were observed regarding trace metals in soils, and concentrations found in the present study were much lower than the ones found in impacted aquifers around the world. No PCB's were detected in groundwater or soils. Nitrate concentrations in groundwater were within the limits recommended by Brazilian legislation.

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Mansouri, Borhan, Nammamali Azadi, Arezo Hashemi Drebadami et Samaneh Nakhaee. « Trace element levels : How Substance Use Disorder (SUD) contributes to the alteration of urinary essential and toxic element levels ». PLOS ONE 19, n^o 2 (5 février 2024) : e0294740. http://dx.doi.org/10.1371/journal.pone.0294740.

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Increasing illicit drug use is one of the main problems in most countries or societies. Monitoring heavy metals and trace elements in this vulnerable group seems to be necessary. Therefore, we assessed the urinary trace element and toxic metals/metalloids concentrations (Zinc (Zn), Iron (Fe), Copper (Cu), Chromium (Cr), Lead (Pb), Cadmium (Cd), Arsenic (As), Nickel (Ni), and Mercury (Hg)) in opium, tramadol, and cannabis users compared to healthy subjects. In this cross-sectional study, patients with substance use disorder (SUD) (n = 74) were divided into four groups: cannabis, tramadol, opium, and mixed (simultaneous use of more than one of the three studied substances), along with a healthy group (n = 60). Urine samples were prepared by dispersive liquid-liquid microextraction method so that heavy metals/metalloids could be measured by ICP-MS. The mean urinary concentration of Cu (48.15 vs. 25.45; 89.2%, p<0.001), Hg (1.3 vs. 0.10; 1200%, p < 0.001), and Zn (301.95 vs. 210; 43.8%, p < 0.001) was markedly lower among patients with SUD. The mean urinary concentration of other elements including As (1.9 vs. 4.1; 115.8%), Cd (0.1 vs. 1.10; 1000%), Cr (6.80 vs. 11.65; 71.3%), Ni (2.95 vs. 4.95; 67.8%), and Pb (1.5 vs. 7.9; 426.6%) were significantly higher among patients with SUD compared to healthy subjects. When sub-groups were compared, no significant differences were observed between their trace element levels (Kruskal-Wallis test, p > 0.05). This can be an indication that regardless of the type of drug, the levels of trace elements are changed with respect to healthy individuals. Our results showed that illicit drug use causes changes in urinary trace element/heavy metal/metalloid levels and highlights the need for monitoring heavy metals and trace elements in individuals with substance use disorder. Assessment of different elements in biological samples of drug dependents may be useful for implementing new prevention and treatment protocols. In case of changes in their levels, complementary recommendations, attention to diet, and periodic assessment of toxic metal levels within treatment programs will be needed.

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Ambreen, Saira, Tasleem Akhtar, Naila Hameed, Isbah Ashfaq et Nadeem Sheikh. « In Vivo Evaluation of Histopathological Alterations and Trace Metals Estimation of the Small Intestine in Bisphenol A-Intoxicated Rats ». Canadian Journal of Gastroenterology and Hepatology 2019 (9 décembre 2019) : 1–7. http://dx.doi.org/10.1155/2019/9292316.

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BPA, a ubiquitously used plasticizer, has become one of the contaminants of emerging concern and causes many serious health implications in humans due to multiple exposure pathways. The current study was aimed at investigating the deformities of structures that arise by exposure of the small intestine to BPA through trace elements estimation of tissues as well as the study of serum profile. Two major groups of Wistar rats were established: one control group and the other experimental group, which was further divided into four groups based on dose (10 mg/kg/bodyweight and 25 mg/kg/bodyweight, respectively) and duration of exposure (6 and 12 weeks, respectively). Histological study of the small intestine showed the distorted structures in the experimental groups. The special staining performed illustrated the accumulation of calcium deposits in the small intestinal tissue in treated groups. Trace metals estimation showed a significant increase in the metallic content of sodium and iron and a decrease in the calcium content in the experimental groups (p=0.05). Serum profiling illustrated an increase in total iron-binding capacity and glucose levels and a decrease in the serum total iron level (p=0.05). An increased expression of a proinflammatory cytokine (IFN-α) was observed in the liver. From all these findings, it was inferred that BPA caused many structural alterations in the small intestinal tissue, which further affected its functioning. The calcium deposits seen through special staining affected the motility of the small intestine and caused its dysfunction. It was also induced from serum profiling that BPA affected the homeostasis of iron and glucose and caused its imbalance. Also, as BPA got absorbed from the small intestine and reached the liver via the blood stream, it caused hepatoxicity in the liver and led to increased inflammatory response by IFN-α against the toxicant.

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Sultana Fahmida, Mozammel Hossain, Mahbubul Morshed*, Maher Negar Priya, Shahzabein Ritu, Umme Samia Antu. « Determination of heavy metals amount in raw milk of Bangladesh ». Global Mainstream Journal 1, n^o 2 (18 octobre 2022) : 1–13. http://dx.doi.org/10.62304/jhmhm.v1i02.25.

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Milk is an indispensable part of the human food regimen that serves several nutritional benefits. Although milk is rich in micronutrients and macronutrients, heavy metal contamination of milk and dairy products is a serious concern. The distribution and deposition of heavy metals and trace elements including Fe, Cu, Zn, Mn, Cd, Cr, Pb, As, etc in different administrative areas of Bangladesh were investigated in this study. All transition metals, regardless of whether they are considered essential or potentially harmful, can have a negative effect on humans and animals if added to the diet in excessive amounts. The samples were prepared for examination by ashing, and after acid digestion, the heavy metals were detected using atomic absorption spectrophotometry. The concentrations obtained in mg/kg were in the range of (0.447 ± 0.043), (0.314 ± 0.077), (0.152 ± 0.025), (0.065 ± 0.022), (0.008 ± 0.002), (0.026 ± 0.003), (0.158 ± 0.027), (0.007 ± 0.001) for iron, copper, zinc, manganese, lead, cadmium, chromium and arsenic respectively. The study was implemented to assess the concentration of heavy metals and if these heavy metals fell below the World Health Organization's permissible standards (WHO). The investigation disclosed high quantities of iron and other metals that were above WHO guidelines. Iron (Fe) concentrations were higher compared to WHO standards (0.5 mg/kg) in raw milk from all divisions except Chittagong. As heavy metal contamination has been a public health concern in recent years, additional research is needed to ascertain the precise origins of heavy metals in raw milk.

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Odewabi, Adesina O., et Martins Ekor. « Levels of heavy and essential trace metals and their correlation with antioxidant and health status in individuals occupationally exposed to municipal solid wastes ». Toxicology and Industrial Health 33, n^o 5 (13 octobre 2016) : 431–42. http://dx.doi.org/10.1177/0748233716669276.

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Recent studies have indicated an increased incidence of toxic neuropathies among waste management workers (WMW) possibly linked to increased detection of heavy metals in municipal solid wastes. The present study evaluated serum levels of some heavy and essential trace metals in relation to oxidant/antioxidant status of WMW. One hundred and twenty-six WMW and 84 non-WMW (control) were recruited. Metal/element concentration was measured by atomic absorption spectrophotometry and oxidant/antioxidant markers were determined using standard procedures. The WMW exhibited significantly ( p < 0.001) decreased ferric reducing ability of plasma (FRAP) and higher levels of ceruloplasmin (Cp) and malondialdehyde. Iron (Fe) and copper (Cu) levels were significantly lower ( p < 0.05) and higher ( p < 0.001), respectively in WMW when compared with control while levels of other trace elements were not significantly different between these groups. Lead (Pb) and chromium levels were significantly higher ( p < 0.001 and p < 0.05, respectively) in WMW while mercury levels were comparable with those of control subjects. In WMW, Cp ( r = −0.182; p > 0.05) and FRAP ( r = 0.277; p < 0.05) negatively and positively correlated with Pb, respectively, while a positive correlation was observed between zinc ( r = 0.230; p < 0.05) and Pb and between Cu ( r = 0.541; p > 0.001) and Fe. Overall, the decreased antioxidant capacity and increased oxidative stress observed in WMW in this study may be related to their blood levels of heavy and essential trace metals. Conscious efforts are required, therefore, to reduce risk and protect WMW from toxic neuropathies and other adverse health consequences of occupational exposure.

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Khayrullaev, P., et U. Farmanov. « ANALYSIS OF TECHNOL SIS OF TECHNOLOGICAL POSSIBILI OGICAL POSSIBILITIES OF FERRIC TIES OF FERRIC RECOVERY BY NON-CONVEN Y NON-CONVENTIONAL REDUCING A AL REDUCING AGENTS ». Technical science and innovation 2019, n^o 2 (2 août 2019) : 50–55. http://dx.doi.org/10.51346/tstu-01.19.2.-77-0021.

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The article discusses the results of the analysis of the technological possibilities of iron recovery of iron-containing concentrate by non-traditional restorers. The restoration of iron from its oxide compounds by direct gas recovery of iron-containing pellets with carbon monoxide is presented. The direct use of the secondary carbon monoxide available in the republic is shown in comparison with the application of complex process processes of carbon monoxide processing and production of intermediate products. It has been established that in order to fully recover iron oxides in the source raw material mass the technological cycle should be repeated several times. As a result, alloys of iron with other metals in iron ore concentrate are formed, as hydrogen is the ideal regenerator.

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Liu, Shuai, Honggao Liu, Jieqing Li et Yuanzhong Wang. « Research Progress on Elements of Wild Edible Mushrooms ». Journal of Fungi 8, n^o 9 (15 septembre 2022) : 964. http://dx.doi.org/10.3390/jof8090964.

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Wild edible mushrooms are distributed all over the world and are delicious seasonal foods, rich in polysaccharides, amino acids, vitamins, and other components. At the same time, they contain many essential trace elements and are highly enriched in heavy metals (compared to green plants and cultivated edible mushrooms). Consumers may be exposed to health risks due to excessive heavy metals in the process of consumption. This is also one of the important factors affecting the import and export of edible mushrooms, which is of great concern to consumers and entry and exit inspection and quarantine departments. In this paper, the contents of four essential trace elements of iron, manganese, zinc, and copper and four harmful heavy metals of cadmium, lead, mercury, and arsenic in nearly 400 species of wild edible mushrooms from 10 countries are reviewed. It was found that the factors affecting the elemental content of edible mushrooms are mainly divided into internal and external factors. Internal is mainly the difference in species element-enrichment ability, and external is mainly environmental pollution and geochemical factors. The aim is to provide a reference for the risk assessment of edible mushrooms and their elemental distribution characteristics.

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Bernardino, Angelo F., Fabiano S. Pais, Louisi S. Oliveira, Fabricio A. Gabriel, Tiago O. Ferreira, Hermano M. Queiroz et Ana Carolina A. Mazzuco. « Chronic trace metals effects of mine tailings on estuarine assemblages revealed by environmental DNA ». PeerJ 7 (7 novembre 2019) : e8042. http://dx.doi.org/10.7717/peerj.8042.

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Mine tailing disasters have occurred worldwide and contemporary release of tailings of large proportions raise concerns of the chronic impacts that trace metals may have on the aquatic biodiversity. Environmental metabarcoding (eDNA) offers an as yet poorly explored opportunity for biological monitoring of impacted aquatic ecosystems from mine tailings and contaminated sediments. eDNA has been increasingly recognized to be an effective method to detect previously unrecognized small-sized Metazoan taxa, but their ecological responses to environmental pollution has not been assessed by metabarcoding. Here, we evaluated chronic effects of trace metal contamination from sediment eDNA of the Rio Doce estuary, 1.7 years after the Samarco mine tailing disaster, which released over 40 million m3 of iron tailings in the Rio Doce river basin. We identified 123 new sequence variants environmental taxonomic units (eOTUs) of benthic taxa and an assemblage composition dominated by Nematoda, Crustacea and Platyhelminthes; typical of other estuarine ecosystems. We detected environmental filtering on the meiofaunal assemblages and multivariate analysis revealed strong influence of Fe contamination, supporting chronic impacts from mine tailing deposition in the estuary. This was in contrast to environmental filtering of meiofaunal assemblages of non-polluted estuaries. Here, we suggest that the eDNA metabarcoding technique provides an opportunity to fill up biodiversity gaps in coastal marine ecology and may become a valid method for long term monitoring studies in mine tailing disasters and estuarine ecosystems with high trace metals content.

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Akintomide, Omolola A., Segun A. Adebayo, Alexandra S. Trahan, Elizabeth Chamberlain et Karen H. Johannesson. « Investigating the Potential Impact of Louisiana Coastal Restoration on the Trace Metal Geochemistry of Constructed Marshlands ». Soil Systems 4, n^o 3 (5 septembre 2020) : 55. http://dx.doi.org/10.3390/soilsystems4030055.

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Coastal restoration through diversion of suspended sediments from the Lower Mississippi River (LMR) into hydrologically isolated marshlands of Mid-Barataria Bay and Mid-Breton Sounds in southern Louisiana has the potential to mobilize lead (Pb), and other trace elements. We investigate the potential impact(s) of the diversion on marsh porewater through analysis of modern riverbank and suspended sediments, compared to sediments from pre-industrial deltaic deposits of LMR. Sequential extraction methods were used to evaluate Pb, cobalt (Co), copper (Cu), nickel (Ni), and zinc (Zn) in the sediments. Our results show that metal contents are higher (e.g., 8- to 10-fold for Pb) in the modern sediments relative to pre-industrial deposits. Also, the reducible fraction, presumably iron/manganese (Fe/Mn) oxides/oxyhydroxides, is the chief reservoir of environmentally available metals. The substantially higher trace metal contents of the modern relative to pre-industrial sediments suggest that the modern sediments contain a sizeable amount of anthropogenic contributions. Furthermore, the concentration of the trace metals in the reducible fraction suggests bioavailability to marsh organisms upon reductive dissolution within the planned, constructed coastal marshes. Still, additional sediment samples from the marshlands during the diversion implementation phase will be necessary to support the preliminary findings in this contribution as it affects coastal marshes and vital local fisheries.

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Oni, S. K., M. N. Futter, K. Bishop, S. J. Köhler, M. Ottosson-Löfvenius et H. Laudon. « Long term patterns in dissolved organic carbon, major elements and trace metals in boreal headwater catchments : trends, mechanisms and heterogeneity ». Biogeosciences Discussions 9, n^o 12 (21 décembre 2012) : 19121–63. http://dx.doi.org/10.5194/bgd-9-19121-2012.

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Abstract. The boreal landscape is a complex, spatio-temporally varying mosaic of forest and mire landscape elements that control surface water hydrology and chemistry. Here, we assess long-term water quality time-series from three nested headwater streams draining upland forest (C2), peat/mire (C4) and mixed (C7) (forest and mire) catchments. Temporal trends in weather and runoff (1981–2008); dissolved organic carbon concentration [DOC] (1993–2010) and other water quality parameters (1987–2011) were assessed. There was no significant annual trend in precipitation or runoff but a significant monotonic increasing trend existed in air temperature and length of growing season. Stream [DOC] was positively correlated with some trace metals (copper, iron and zinc) and negatively with several other chemical parameters (e.g. sulfate, conductivity, calcium). Both sulfate and conductivity showed declining trends, while a significant increase was observed in pH during winter and spring. Calcium and magnesium showed monotonic decreasing trends. The declining trajectories of stream base cation and sulfate concentrations during other times of the year were not accompanied by changes in pH and alkalinity. Water temperature increased significantly both annually and in most months while iron and DOC concentrations showed significant increases in autumn months. Though all streams showed significant positive trends in [DOC] in autumn, only C2 had a significant annual increasing trend. There was also a shift in the magnitude of variability in spring [DOC] and increasing trend of summer baseflow [DOC] in C2 and C7.

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