Total Manganese Content Research Articles

SnO2/MnOx composite systems as VOCs sensors: Influence of manganese chemical state and distribution on functional performances

SnO2/MnOx nanocomposites with manganese content up to [Mn]/([Mn]+[Sn]) = 10 mol.% were prepared using chemical precipitation and impregnation-annealing techniques and examined using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, mass-spectrometry with inductive coupled plasma. Manganese distribution between the bulk and the surface of SnO2 crystal grains depending on the total manganese concentration was determined and the chemical state of both type (bulk and surface) manganese cations was identified. Strong correlations of sensor signal toward C1 volatile organic compounds (methanol, formaldehyde, formic acid) and C1–C4 carbonic acids (formic, acetic, propionic, butyric) with the total manganese content, manganese distribution and chemical state were revealed.

Essential minerals and anti-nutritional compounds in plant-based burgers using the infogest in vitro digestion protocol

Plant-based burgers (PBB) are becoming a worldwide popular alternative to meat-based burgers (MBB). Still, their mineral composition can differ significantly depending on the ingredients used, the effect of the matrix, and the chemical form of the elements that influence solubility in the digestive tract. Thus, the study evaluated the total content and bioaccessibility of calcium (Ca), iron (Fe), magnesium (Mg), manganese (Mn), and zinc (Zn) in commercial samples of PBB and MBB. Tests used acid mineralization in an analytical microwave, following INMETRO for method validation. Results, in mg/100 g, of Ca (22.2–144), Fe (3.52–12.9), Mg (21.6–120), Mn (<LOQ-2.26), and Zn (0.91–3.47) observed for PBB indicated extensive variation; and for MBB composition of Ca (<LOQ-8.15), Fe (1.79–2.06), Mg (18.2–20.1), Mn (<LOQ), and Zn (5.42–6.86) presented low variation. The percentage of bioaccessibility, was significant in chickpea PBB for Ca (31.5 %), Fe (51.2 %), Mg (81.0 %), Mn (61.7 %), and Zn (48.0 %). MBB also showed bioaccessibility for Ca (92.4 %), Fe (60.0 %), and Mg (83.6 %). Anti-nutritional compounds such as myo-inositol phosphates and total dietary fiber did not affect negatively mineral bioaccessibility in PBB evaluated. To date, this study is the first to carry out in vitro digestion simulation assays using the INFOGEST 2.0 protocol to evaluate the bioaccessibility of essential minerals in PBB and anti-nutritional compounds. In addition, the data presented can help manufacturing companies develop more nutritious and competitive plant-based meat analogs (PBMA) as PBB. They can also influence dietary recommendations and public health policies by identifying foods nutritionally more suitable, which has a positive impact on public health. With this information, consumers can make more informed and responsible food choices, based on nutritional needs.

Chemical Fractionation of Manganese in Commercial Coffee Samples from Conventional and Organic Cultivation Systems

Coffee, a source of useful nutrients, is predominantly consumed as an infusion. Because of this, the availability of these nutrients is influenced by their solubility, which could be affected by cultivation methods. This study investigates the impact of Brazilian-regulated organic cultivation practices on manganese. It evaluates total concentration, fractionation, and infusion extractability using semi-selective extraction and flame atomic absorption spectrometry (FAAS) for analysis. The average total manganese concentrations were 45.5 ± 11.2 mg kg−1 in conventional coffee and 64.7 ± 9.2 mg kg−1 in organic coffee. The higher manganese levels in organic coffee may be attributed to soil conditions that are beneficial to organic farming. Principal component analysis revealed distinct differences in manganese fractionation, underscoring the impact of cultivation methods on manganese metabolism and storage. Despite these disparities, the manganese levels in coffee infusions and the fraction available for absorption exhibited no significant variation between conventional and organic cultivation group samples.

Heavy Metals Contamination in Snow Cover of Pavlodar (Kazakhstan)

A study of the concentration of heavy metals in snow cover was carried out in Pavlodar in the area of influence of the Pavlodar Petrochemical Plant and other industrial facilities. Significant excesses of background concentrations of manganese, chromium, vanadium and other metals were detected. The distribution of metals in the snow cover showed that the elements have high values near the oil refinery and decrease at a distance of 700 m. The possible influence of other industrial enterprises and the direction of winds from CHP-3 are also noted. Manganese and barium show more stable values, and chromium, zinc, lead and cadmium have increased concentration near JSC “Kaustik”. The total concentration of manganese, strontium, cobalt and arsenic varies slightly across all sites, indicating uniform contamination by these substances. Lead is highest in industrial areas and in populated areas with highways. Aluminum and iron are widespread, with the lowest values in the Zhanaul village at a distance of 3 km from the Petrochemical Plant. The results of the study highlight the importance of controlling and monitoring heavy metal pollution and the need to take measures to reduce anthropogenic impacts on the natural environment.

Приготування і характеризація референс-матеріалу для визначення загального вмісту та рухомих форм металічних елементів у ґрунтах

Reference material of soil for determination of total content of copper, iron, manganese, nickel, and zinc, according to ISO 11466-2001, and for the operationally defined method of determination of exchangeable forms of these elements according to series of standards DSTU 4770, with ammonium acetate as an extractant is prepared and characterized. The studied material demonstrated sufficient homogeneity to exchangeable forms of metals and for the total content of copper, nickel, and zinc. The homogeneity of the material to manganese and iron is insufficient due to the presence of these metals in non-uniformly distributed magnetic microparticles (&lt;10 μm). An interlaboratory experiment, performed to obtain assigned values of the sample characteristics, demonstrated sufficiently good agreement between the laboratories. An uncertainty of the assigned value corresponds to 30–50% for exchangeable forms of copper and nickel and 10–13% for exchangeable forms of iron, manganese, and zinc. An expanded uncertainty of assigned values of the total content of copper, nickel, and zinc is sufficient for the application of the material for methods validation and internal quality control.

The Responses of C, N, P and Stoichiometric Ratios to Biochar and Vermicompost Additions Differ from Alfalfa and a Mine Soil

The use of ecological stoichiometry is quite effective for exploring the nutrient dynamics and relationships between plants and soils. However, the way that the plant and soil stoichiometry changes with soil remediation in mining ecosystems remains unclear. Biochar and vermicompost are generally applied to remediate contaminated soil. In this study, a pot experiment was conducted with a mine soil planted with alfalfa. Biochar (B) and vermicompost (V) were added to the soil separately in three different proportions, equivalent to application rates (w/w) of 0% (control, CT), 2.5% (low rate, l), and 5% (high rate, h). This resulted in nine treatments, including control (CT), Bl, Bh, Vl, Vh, BlVl, BlVh, BhVl, and BhVh. The carbon (C), nitrogen (N), and phosphorus (P) concentrations and stoichiometric characteristics of the alfalfa aboveground parts (plant) and soil were investigated. The results showed that biochar application significantly increased the concentrations of soil organic C (SOC), soil total N (TN), soil total P (TP), soil C:N, and plant P concentration, but decreased plant N concentration, and plant C:P and N:P ratios. The effects of vermicompost addition on SOC, soil TN, TP, and stoichiometric characteristics depended on the biochar addition rates, but it increased plant N concentration and N:P, and decreased plant C:N under the condition of low biochar addition. Additionally, the plant N concentration was negatively correlated with soil N and total manganese (Mn) concentrations, whereas there was a positive correlation between plant and soil P concentrations. The soil total and available cadmium (Cd) were positively correlated with plant N concentration but negatively correlated with plant P concentration. The results indicated that the stoichiometric characteristics of plants and soil had diverse responses to biochar and vermicompost additions, and different soil heavy metal elements. Biochar and vermicompost application improved external P and N utilization by plants, respectively. Vermicompost addition enhanced biological N fixation in alfalfa. These findings suggest that vermicompost addition could be an optimal method by which to promote vegetation restoration in mine soils with poor N levels, and that biochar could be applied to low-P soils. The effects of heavy metals on plant and soil stoichiometric characteristics should be taken into consideration. Consequently, this study will provide scientific references for biochar and vermicompost applications in alfalfa planting and management, and vegetation restoration in mining areas.

Health risk assessment of exposure to various vapors and fumes in a factory of automobile manufacturing

This study aimed to comprehensively evaluate the health risk of exposure to various vapors and fumes in a factory of automobile manufacturing. This study was performed in 2021 on 115 workers. Vapors and fumes were gathered by the adsorbent tubes of activated charcoal and mixed cellulose esters (MCE) membrane filter, respectively. The flow rate for vapors and fumes were between 0.05 and 0.20 L per min and 1 to 4 L per min, respectively. After preparing, samples were analyzed. To assess the non-cancer and cancer risk of the pollutants, the method proposed environmental protection agency (EPA) was applied. The total concentration of copper (1.031 ppm), manganese (0.114), and 2-butoxyethanol (91.767 ppm) were found to be higher than The threshold limit values (TLVs). The values of non-cancer risk (HQ) due to exposure to vapors of benzene (6.583), toluene (1.396), ethyl benzene (1.212), xylene (31.148), 2-butoxyethanol (89.302), 2-propanol (4.695), 1,2,3-trimethylbenzene (1.923), copper (2.336), manganese (715.82), aluminum (3.772), and chromium (107.066) were higher than the acceptable limit. Moreover, the estimated LCR for benzene (2.15 × 10−4), ethyl benzene (3.97 × 10−4), vinyl chloride (1.25 × 10−4), and chromium (2.11 × 10−2) were higher than the threshold risk level set by EPA. It is emphasized that preventive measures are performed.

Impacts of Elevated Ozone and Ozone Protectants on Plant Growth, Nutrients, Biochemical and Yield Properties of Turnip (Brassica Rapa L.)

ABSTRACT An experiment was conducted at Woodhouse farm, Horticultural Research Station, Ooty, during October 2017 to March 2018 to quantify the impact of elevated ozone and ozone protectant spray on plant growth, nutrients, biochemical and yield properties of turnip crop. The experiment was laid out in a factorial completely randomized block design and was replicated thrice. Elevated ozone exposure on turnip significantly reduced the plant height, tuber size, tuber weight, chlorophyll ‘a,’ chlorophyll ‘b’ and total chlorophyll content as well as the nutrient content of plant, viz., total nitrogen, total potassium, total manganese, iron, zinc and copper, also affected. Elevated ozone exposure significantly increased the antioxidant enzyme activity like catalase and peroxidase activity in addition to increment in total phosphorus content in leaf tissues. However, ozone protectants played a major role in nullifying the tropospheric ozone effect on growth and development, physiological traits and yield of turnip while tested with panchagavya performed better followed by neem oil and ascorbic acid.

Exposure of the Portuguese population to metals and metalloids: results from a national study

Metals and metalloids are elements present in the environment that can originate from natural and anthropogenic sources. However, exposure to some of these elements can cause adverse health effects due to their toxicological potential. As such, it is important to assess their levels in the human body, which can be done through human biomonitoring. Several studies assessed these elements’ levels in the Portuguese population, but were mainly focused on hotspots or specific groups. As such, the aim of this work was to assess the exposure to metals and metalloids in the Portuguese population using samples collected in the study &amp;#x22;Exposure of the Portuguese Population to Environmental Chemicals: a study nested in INSEF 2015&amp;#x22; (INSEF-ExpoQuim). INSEF-ExpoQuim was an epidemiologic study including 297 participants aged 28-39 years, living in Portugal for &amp;#x2265; 12 months and able to follow an interview in Portuguese. Fieldwork was developed between June 2019 and February 2020 following the guidelines of the HBM4EU project. First morning urine samples were collected along with data on sociodemographic characteristics, living conditions and residential history, habits/lifestyle, nutrition, health, occupation and substance specific information. Total concentrations of arsenic (As), lead (Pb), cobalt (Co), copper (Cu), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se) and zinc (Zn) were determined by inductively coupled plasma mass spectrometry. As, Cu, Mo, Se and Zn were detected in the majority of the samples analysed, while Mn was detected in around half and Pb, Co and Ni were detected in less than half. Results will be presented, including a description of the biomarkers’ levels in the Portuguese population. This study is the first developed in Portugal to provide an assessment of the exposure at a national level and its results may support the development and implementation of policy measures aimed at minimizing exposure and improving the population’s health.

Effect of Pseudomonas fluorescens in manganese uptake by chickpea (Cicer arietinum L.) cultivars infected by root-knot nematodes (Meloidogyne incognita)

Chickpea (Cicer arientinum L.) is one of the most dominant pulse crops in India, which contributes 38 percent of the area and 50 percent production of pulses compare to the total pulse production of India. Chickpea contains protein-2.1%, carbohydrates-61.5%, and fat-4.5% and more iron, calcium and niacin content. The main constrain of chickpea production due to parasitic nematodes (Meloidogyne incognita) is about 14% of total global production in annual yield loss. Pseudomonas fluorescens is a bacterial bio-agent that can help in nematode suppression in chickpea plants. This experiment was conducted to experience the differences, if any, in manganese content concerning chickpea inoculated with M. incognita with a combination of Pseudomonas fluorescens as a bioagent, where different treatments of nematode, bacteria, and chemicals are used sustaining the enhancement of disease resistance in chickpea cultivars RSG 974, GG 5, GNG 2144. The total manganese content of chickpea variety GNG 2144 was found highest in treatment, where only bacteria (P. fluorescens) was inoculated, i.e., 6.44 mg/100g of a root, followed by GG 5, i.e., 5.63 mg/100g of root and RSG 974 was, i.e., 4.14 mg/100g of root respectively. Application of Pseudomonas fluorescence combined or alone gradually increased the manganese concentration in roots of chickpea plants i.e., RSG 974 (4.14 mg/100g), GG 5(5.63 mg/100g), GNG 2144 (6.44 mg/100g) compared to the health check.

Bioaccessibility and Toxicity Assessment of Polycyclic Aromatic Hydrocarbons in Two Contaminated Sites.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous soil contaminants, and their bioaccessibility determines their environmental risks in contaminated land. In the present study, the residual concentrations of PAHs in the soils of two industrial sites were determined, and their bioaccessibility was estimated by the hydroxypropyl-β-cyclodextrin extraction (HPCD) extraction method. The results showed heavy PAH contamination at both site S1 (0.38-3342.5mgkg-1) and site S2 (0.2-138.18mgkg-1), of which high molecular weight (HMW) PAHs (4-, 5-, and 6-ring compounds) accounted for approximately 80%. The average bioaccessibility of PAHs at sites S1 and S2 was 52.02% and 29.28%, respectively. The bioaccessibility of certain PAH compounds decreased with increasing ring number of the molecule. Lower PAH bioaccessibility was detected in loamy and silty soil textures than in sandy soil. Moreover, among the soil properties, the dissolved organic matter, total organic carbon, total potassium, and total manganese concentrations had significant effects on the bioaccessibility of PAHs. The toxicity analysis showed that the composition and bioaccessibility of PAHs could affect their potential toxicity in soil. We suggest that bioaccessibility should be taken into consideration when assessing the toxicity of PAHs in soil, and more attention should be given to low-ring PAHs with high bioaccessibility.

Comprehensive Analysis Revealed the Specific Soil Properties and Foliar Elements Respond to the Quality Composition Levels of Tea (Camellia sinensis L.)

C. sinensis cv. Sijichun is a representative Taiwanese low-altitude tea cultivar native to central Taiwan. To enrich the taste of tea in a geographically disadvantaged area, soil management became necessary but was obscure. The purpose of this study was to screen the main soil factors that influence the quality composition levels of tea to optimize the efficiency of tea tree horticulture. Soil and tea leaf samples collected from 20 tea plantations determined thirteen soil properties, nine leaf element nutrients and aluminum, and five main extractable quality compositions, including polyphenols, catechins, flavones, free amino acids, and caffeine in tea infusion. Pearson’s correlation analysis and principal component correlation analysis showed that soil available nutrients cannot respond to the concentration of corresponding essential elements in tea leaves; nevertheless, adequate leaf macronutrients and Zn could enhance polyphenol, free amino acid, and caffeine contents, but decreased flavone contents, and showed their consistent effect by soil characteristics. Of note, soil pH, EC, exchangeable calcium, exchangeable magnesium, total concentration of manganese, and total concentration of copper were shown as significant impact factors on free amino acid content. In summary, regulating the pH of soil under 3.51–5.21 in our study and managing soil effective Ca, Mg, and Zn supply could help to obtain a greater umami taste of tea.

Assessment of environmental pollution of heavy metals deposited on the leaves of trees at Yazd bus terminals.

There is a lack of information on the effect of urban transport activities in emitting heavy elements into the environment. This research assesses the concentrations of some heavy elements in the deposited atmospheric dust at Yazd bus terminals in Yazd, Iran. So, 34 falling dust samples were collected from the leaves of trees planted near the bus terminals. Following the digestion by nitric acid, the total concentrations of cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), chromium ‬(Cr), and manganese (Mn) were determined in the dust by atomic absorption spectrometry. The map representing the spatial distribution of the metals was plotted, and their sources were identified using Pearson's correlation coefficient, principal component analysis, and cluster analysis. The results indicated that the mean concentrations of the heavy metals in the dust deposited on the tree leaves were in the order of Cd < Co < Ni < Pb < Cu < Zn < Cr < Mn. The map representing the spatial distribution of the heavy metal concentrations illustrated that the abundance of metals in different stations varied with their location. Two main sources were detected for the heavy metals in the deposited dust. Co, Cd, Mn, and Ni had anthropogenic and lithogenic sources while Pb, Zn, Cr, and Cu were emitted by traffic and industrial activities. Enrichment factor, contamination factor, integrated pollution index, and risk index were estimated at low to extremely high levels of pollution in residential, commercial, green space, and environmental uses. Based on the results, the growth of industrialization and human activities contribute to the heavy metal contamination of the environment emitted into the atmosphere in Yazd.

Effects of zinc-aluminium injection on corrosion behaviour and semiconductor properties of carbon steel in the PHT system of PHWR.

Carbon steel is widely used as the piping of the primary heat transport system (PHT) in pressurized heavy water reactors (PHWR). Effects of zinc/aluminum treatment and simultaneous injection of zinc and aluminum on corrosion behavior and semiconductor properties of oxide films formed on carbon steels were characterized by the gravimetric method, potentiodynamic polarization scan, EIS, Mott–Schottky test, SEM, EDS mapping, XPS analysis and photocurrent response measurement. The results showed that all the metal cation ions treatment can improve the corrosion resistance of oxide films in varying degrees. 20 ppb Zn2+ had the greatest enhancement in corrosion resistance, followed by 20 ppb Zn2+ + 20 ppb Al3+. ZnFe2O4, FeAl2O4 and ZnAl2O4 were detected to be new spinel phases generated in oxide films. The oxide films on the surface of carbon steel all demonstrated n-type semiconductor properties. It was worth noting that the total content of manganese and zinc in the oxide film played an important role in the corrosion resistance of carbon steel.

Manganese fractionation analysis in specific soil and sediment samples

Manganese has been determined in soil- and sediment samples taken from selected regions with high manganese concentrations anthropogenic and/or geogenic. The total content of manganese in chosen sediment- and soil samples has been determined applying FAAS after microwave digestion and the manganese fractions after sequential extraction procedures using galvanostatic stripping chronopotentiometry. The highest content of manganese has been determined in sediment from Hôrka (6243.6 ± 56.2 mg kg-1), while the lowest value has been obtained in the sediment from Kráľová (278.6 ± 3.9 mg kg-1). Using a modified Tessier’s procedure it was found, that manganese in sediments from Kráľová is associated mainly with the carbonate fraction (&gt;50%), while in sediments from Lozorno and Hôrka it is associated primarily with the Mn and Fe oxide fraction (80% and 42% respectively).

Milk productivity of cows and the content of the metal-ligand forms of iron

The milk productivity of animals was evaluated and the content of the metal-ligand forms of iron was studied against the background of changes in the total content of manganese in the blood serum of dairy cows using the hybrid technique (HPLC-ICP-MS). For this purpose, groups were formed for comparing animals with low-normal values of manganese (Mn concentration up to the 25th percentile) and high-normal values (Mn concentration above the 75 th percentile) according to the results of a previous study. The Mn content in the blood serum of all animals was within the physiological normal range. Analysis of the data obtained showed that high-normal levels of manganese in the blood were accompanied by a significant decrease in the indicators of milk productivity of cows. The metal-ligand forms of iron have undergone significant changes. Changes in metal ligand homeostasis can be considered early biomarkers for predicting the state of mineral metabolism to increase productivity.

Assessing phytoremediation potentials of selected plant species in restoration of environments contaminated by heavy metals in gold mining areas of Tanzania

This study assessed and classified the phytoremediation potentials of selected plant species around gold mining areas in restoring the environments contaminated by heavy metals. The geographic focuses of the study were the Golden Pride Gold Mine (GPGM) and Geita Gold Mine (GGM) in Tanzania. The shoots and roots of plant species surrounding the mining areas and the samples of associated soils were collected and analysed for total concentrations of lead (Pb), chromium (Cr), cadmium (Cd), copper (Cu), arsenic (As), manganese (Mn) and nickel (Ni) using Atomic Absorption Spectrophotometer (AAS) and UV-VIS spectrophotometry. Results indicated that the soils from study areas were loamy textured and slightly acid (pH 6.1–6.5), soil organic carbon and organic matter were low (0.6–2.0%), total nitrogen was very low (<0.10%), phosphorous ranged from low (6–12 mg kg−1 soil) to high (13–25 mg kg−1 soil), and cation exchange capacity ranged from low (6.0–12.0 cmol(+) kg−1 soil) to medium (12.1–25.0 cmol(+) kg−1 soil). In assessing heavy metals using plant parts, the roots of giant rats-tail grass (Sporobolus pyramidalis) accumulated highest Pb (757.78 μg g−1), Creeping Blepharis (Blepharis maderaspatensis) the Cd (158.11 μg g−1), lantana (Lantana camara) the As (68.61 μg g−1), and leuceana (Leucaena leucocephala) accumulated higher Mn (2734.61 μg g−1) and Ni (4464.33 μg g−1). In shoots, L. leucocephala accumulated higher Cr (1276.67 μg g−1) and higher Cu (2744.44 μg g−1) in L. camara. Although S. pyramidalis, M. repens, L. camara, B. maderaspatensis and L. leucocephala are likely to pose hazards to herbivores (grazing animals) while entering the food chain, they are still potential hyperaccumulators thus can be used to decontaminate metalliferous affected soils. Blepharis maderaspatensis has never been reported anywhere as Pb, Cd, Cu, Mn and Ni uptake plant hence this can be regarded as a new finding.

Features of the Distribution of Manganese in Soils of the Prichulym Taiga in Tomsk Region During Forest Logging

In the course of the summer expedition, soil samples were taken from the upper, the most ‘active’ for migration and pollution by chemical elements, horizon in the taiga zone of Zyryanskiy district, Tomsk region. Soils were sampled in two plots: in a typical taiga forest and in the area after selective logging carried out six years ago. The selected soil samples were analyzed for the presence and total content of manganese. As a result of statistical data processing, the average value of the content of this element was obtained. Changes in the species composition of vegetation in the logged area could affect the redistribution of the considered chemical element in the soil. For a complete picture of the deposition and the reasons for possible migration of manganese in the upper layer of the soil horizon, the acid-base conditions and the organic component (humus) were additionally determined in the soil samples. The global indicators of the world’s soils – clarke values – were used as standards to compare with the average values of the manganese content in soil. The obtained average values of manganese in the upper horizon of soils in the studied areas were compared with respect to the data on the content of manganese in soils of the taiga forest zone of Eurasia. The southeast of Tomsk region is included in this zone. Based on the ecological and geochemical analysis, the reasons for the change in the content of manganese and the degree of its dangerous impact have been revealed. This characteristic made it possible to interpret the data obtained on the manganese content in the soil of the study areas, as well as to assess the state of the environment after anthropogenic transformation and other possible factors.

Coupled electrocoagulation and oxidative media filtration for the removal of manganese and arsenic from a raw ground water supply

The application of electrocoagulation (EC) as a standalone technology, as well as coupled with oxidative media filtration was investigated for the removal of arsenic and manganese from a community’s groundwater supply. The effects of metal loading (ML), current density and flocculation time was investigated, in addition to the subsequent use of GreensandPlus™filtration. Effective removal of arsenic was yielded to levels well below World Health Organization limits, with final concentrations below 3 μg L−1, from an initial concentration of 9.77 μg L−1. The optimal ML, or coagulant dose, was observed to be 10 mg L−1, with very little removal at MLs below 2 mg L−1. EC was not as effective for manganese removal, with only 10% reductions at an ML of 10 mg L−1. Further manganese reductions were yielded during flocculation, yielding a final total manganese concentration of 98.97 μg L−1, below both the WHO and Health Canada maximum allowable concentration for drinking water. When coupled with oxidative media filtration, arsenic was nearly completely removed, with final concentrations below 0.1 μg L−1. While the mechanism of arsenic removal was primarily associated with the iron coagulant floc formation, manganese removal was attributed to the catalyzed oxidation reduction reaction with the manganese dioxide media. Comparative studies using conventional coagulant resulted in arsenic concentration to decrease to 4.4 μg L−1, over an order of magnitude greater than those achieved with EC.

Features of the content of manganese in natural waters in the south of the Far East (on the example of the Jewish Autonomous Region)

The article provides data on the content of total manganese (Mn) during the 2019 summer in the surface waters of the Bira River and its tributaries, which are located in the North of the Jewish Autonomous Region (JAR), a biogeochemical province in terms of excess iron (Fe) and Mn in the water. The aim of the study was to examine the distribution of Mn and to reveal its concentration in surface watercourses taking into account the geological features and natural conditions of the region. Water samples were taken at 11 stations from the left tributaries of the Bolshaya Bira river. A photometric method with formaldoxime was used to determine the gross Mn content in water in October 2018. The atomic absorption spectrometer “Kvant-2 AT” was used in 2019. Very high concentrations of total Mn were revealed in the waters of rivers in the north-western part of the region in the area of the Mn ore deposit. It has been shown that in the rivers located to the northeast of the deposit, the metal concentration sharply declines. In the eastern swampy part of the region, the Mn content in the river water of the Ikura River sharply increases up to 0.139 mg/dm3. The results of surface water samples from the Bira River basin confirmed the previously identified distribution of Mn levels in the waters of the River and its tributaries in accordance with natural conditions.