Search

Manganese (Mn) is essential for plant growth, as it serves as a cofactor for enzymes involved in photosynthesis, antioxidant synthesis, and defense against pathogens. It also plays a role in nutrient uptake, root growth, and soil microbial communities. However, the availability of Mn in the soil can be limited due to factors like soil pH, redox potential, organic matter content, and mineralogy. The excessive use of chemical fertilizers containing Mn can lead to negative consequences for soil and environmental health, such as soil and water pollution. Recent research highlights the significance of microbial interactions in enhancing Mn uptake in plants, offering a more environmentally friendly approach to address Mn deficiencies. Microbes employ various strategies, including pH reduction, organic acid production, and the promotion of root growth, to increase Mn bioavailability. They also produce siderophores, anti-pathogenic compounds, and form symbiotic relationships with plants, thereby facilitating Mn uptake, transport, and stimulating plant growth, while minimizing negative environmental impacts. This review explores the factors impacting the mobility of Mn in soil and plants, and highlights the problems caused by the scarcity of Mn in the soil and the use of chemical fertilizers, including the consequences. Furthermore, it investigates the potential of different soil microbes in addressing these challenges using environmentally friendly methods. This review suggests that microbial interactions could be a promising strategy for improving Mn uptake in plants, resulting in enhanced agricultural productivity and environmental sustainability. However, further research is needed to fully understand these interactions' mechanisms and optimize their use in agricultural practices. [ABSTRACT FROM AUTHOR]

In this paper, Scots pine (Pinus sylvestris L.) roots grown in soils with and without contamination from emission of a plant steel were analyzed for Fe and Mn, as well as the shoots and needles with and lacking pollution. The aim was to assess the content of Fe and Mn in soils under given conditions, and the interaction between pine plant and soil in terms of metal accumulation in the fine roots, annual shoots, and annual needles. The iron content in the soil of polluted areas does not contrast with its control amount. Conversely, the iron content in fine pine roots under contamination conditions is 2.1–4.4 times higher than the control values. There were no significant excesses of the manganese content in the soil in polluted conditions compared to the control, but its content in the 0–20 cm soil layer is 27–32 times higher than the background concentrations. The iron contentment in belowground (fine roots) and aboveground (annual shoots and needles) parts of pine trees in a context of contamination is higher than the control values (2.1–4.4 and 1.50–1.54 times, respectively). The manganese content in fine pine roots under contamination conditions is 2.8–10.7 times less than in control, while its content in shoots and needles is higher (2.23–2.76 times) in comparison with the control. Based on the values of the biological accumulation and migration coefficients, what in each case slighter than one, for Scots pine the iron represent not an element that actively accumulates. Nevertheless, for manganese, this stock model is valid only for fine roots, whereas under the contaminated environment, the metal mobility steepen, and the migration pattern shifts towards increased manganese accumulation in the aboveground part of pine trees. [ABSTRACT FROM AUTHOR]

Summary: A restoration trial of grassy woodland on former agricultural land applied carbon at a standard rate (840 g C/m2/year) and at a high rate (4,200 g C/m2/year), to test whether further benefits to native plants and suppression of exotics would emerge. Carbon addition at the high rate reduced plant cover further than the standard rate but led to severe loss of plant species; it also reduced soil pH. Soil Al, Fe and Mn levels increased across the gradient of C addition, which would be consistent with the reduction in soil pH for Al and Mn, and a decrease in soil redox potential for Mn and Fe. Nutrient analysis of leaf tissue confirmed that uptake of Fe and Mn increased over the range of C addition, with the concentration of Mn in the high carbon treatment exceeding the threshold for toxicity for a range of species. The soil and plant tissue data are consistent with the induction of increased soil acidity and of stronger reducing conditions in the soil by high level of carbon addition and localised soil flooding. Plant uptake of Mn to toxic levels occurred subsequently, leading to negative effects on plants; aluminium phytotoxicity may also have occurred. [ABSTRACT FROM AUTHOR]

Background and Aims Micronutrient deficiency in cereals is a problem of global significance, severely reducing grain yield and quality in marginal soils. Ancient landraces represent, through hundreds of years of local adaptation to adverse soil conditions, a unique reservoir of genes and unexplored traits for enhancing yield and abiotic stress tolerance. Here we explored and compared the genetic variation in a population of Northern European barley landraces and modern elite varieties, and their tolerance to manganese (Mn) limitation. Methods A total of 135 barley accessions were genotyped and the genetic diversity was explored using Neighbor–Joining clustering. Based on this analysis, a sub-population of genetically diverse landraces and modern elite control lines were evaluated phenotypically for their ability to cope with Mn-deficient conditions, across three different environments increasing in complexity from hydroponics through pot experiments to regional field trials. Key Results Genetically a group of Scottish barley landraces (Bere barley) were found to cluster according to their island of origin, and accessions adapted to distinct biogeographical zones with reduced soil fertility had particularly larger Mn, but also zinc (Zn) and copper (Cu) concentrations in the shoot. Strikingly, when grown in an alkaline sandy soil in the field, the locally adapted landraces demonstrated an exceptional ability to acquire and translocate Mn to developing leaves, maintain photosynthesis and generate robust grain yields, whereas modern elite varieties totally failed to complete their life cycle. Conclusions Our results highlight the importance of gene pools of local adaptation and the value of ancient landrace material to identify and characterize genes that control nutrient use efficiency traits in adverse environments to raise future crop production and improve agricultural sustainability in marginal soils. We propose and discuss a model summarizing the physiological mechanisms involved in the complex trait of tolerance to Mn limitation. [ABSTRACT FROM AUTHOR]

An increase in human population coupled with urbanization, has resulted for higher demand in meat per capita. Meat and meat products are important for human diet as they provide a great part of nutrients, including necessary trace elements which act as micronutrients. The present study focuses on the concentration of trace elements (chromium, copper and manganese) in the meat of goats (40 weeks age) reared in the three targeted zones of West Bengal, where high heavy metal concentrations in soil and water is a matter of concern. Soil, water and chevon samples were collected from three targeted zones of West Bengal. The meat samples were taken from free range goats grazing locally. Over a span of six months samples were collected, digested and analyzed by atomic absorption spectrophotometry. The mean values of heavy metals in soil samples ranged from 29.96-49.260 ppm of chromium, 14.65 to 38.3 ppm for copper and 198.6 to 482 ppm for manganese. The mean values of heavy metals in water ranged from 0.006-0.02 ppm for chromium, 0.0024 to 0.0180 ppm for copper and 0.068 to 0.436 ppm for manganese. Soil samples revealed high concentration of chromium and copper whereas water samples revealed high concentration of manganese. These levels did not impact the edible quality of meat. Hence advocating that risks associated with chevon consumption from goats (40 weeks age) reared in areas having high heavy metal residual content are negligible and consumption of such meats should not necessarily cause any dilemma. [ABSTRACT FROM AUTHOR]

Enhancement of manganese (Mn) availability in saline and Mn-deficient soils is very important for plant growth. An experiment was carried out to evaluate the effect of Pseudomonas sp. rhizobacteria (P0 (control), P1, P2 and P3) and Mn (0 and 10 mg Mn kg−1 soil) on the distribution of Mn in the rhizosphere of pistachio seedlings under salinity stress (0, 1000 and 2000 mg NaCl kg−1 soil). The results showed that salinity decreased the dry weight, Mn uptake and chlorophyll content of the pistachio seedlings. However, inoculation with rhizobacteria increased these parameters in saline conditions. Application of rhizobacteria increased the availability of Mn in the rhizosphere soil. The use of rhizobacteria decreased the residual-Mn form in the rhizosphere. Inoculation with rhizobacteria increased the percent of Mn2+ and MnCl+ species in the soil solution. However, pistachio seedlings inoculation with rhizobacteria increased the contents of Mn available forms in the rhizosphere soil. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Slovenica is the property of Biotechnical Faculty of the University of Ljubljana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Availability of micronutrients in the right amount and proportion is vital for optimum nutrients utilization by diversity of plants. However, the current fertilizer recommendation for plants in Northern Nigeria is only for macronutrients and continuous application of one or two macronutrients may deplete the soil reserve of other nutrients; micronutrients inclusive, due to nutrients antagonism and consequently, reduce plant yield. For these reasons, this study was conducted to assess the profile distribution of zinc, copper, iron and manganese in selected soils of Kano state, Nigeria. Thirteen profile pits were sunk across thirteen (13) local government areas of Kano state. A total of (39) thirty nine composite samples were collected according to the pedogenic horizons at the different locations. In addition to the determination of other physical and chemical properties, available micronutrients; Cu, Fe, Zn and Mn were extracted with 0.1N HCl and the concentration of nutrients measured with atomic absorption spectrophotometer (AAS). Data obtained were subjected to Generalized Linear Model (GLM) procedure of Statistical Analysis Software (SAS) laid down in a randomized complete block design (RCBD). Significantly different means were then separated using Duncan multiple range test. Results obtained revealed that although Fe and Mn contents were adequate for crop production, Zn and Cu values ranges from 0.79 to 1.14 mg kg-1 and 0.76 to 1.11 mg kg- respectively and were rated as inadequate in all the soils of the study area as such, supplementary application of these micronutrients could be beneficial for plant diversity development. Similarly, addition of organic residues as well as including Cu and Zn in fertilizer blends to be used in soils of the study area is necessary to improve plant diversity development. However, result of plant diversity is indicated with the Sahel Savanna having1,086 species, Sudan Savanna 1,116 species and 1,264 species in the Northern Guinea Savanna respectively. [ABSTRACT FROM AUTHOR]

Introduction and objective: Manganese (Mn) is an essential element for the plant and it is necessary for maintain physiological processes, notably photosynthesis, but its higher content in the soil may negative affect the plant, and consequently human health. The objective of this study was to examine the Mn accumulation in edible parts of tested food crops growing on soils near two Mn ore deposits in Bužim municipality (active Mn mine Bužim and Mn ore deposits Radostovo). Methods: Atomic Absorption Spectroscopy (AAS) was used to determine Mn content in soils and edible parts of different food crops; onions, cabbage strawberry, garlic, potato, pepper, beans and raspberry. Results: The content of Mn available forms, and accumulation in edible parts of examined food crops was significantly higher in soils in the area around Mn mine Bužim although the content of the total Mn in the soils at the site Radostovo were much higher. Considering that soils in the area around Mn mine Bužim are much more acidic than soils at the site Radostovo, it is evident that soil pH is one of the key factors in the assessment of Mn availability in soil. The results of study also showed that the content of Mn in edible parts of all tested food crops did not exceed the toxic value for Mn in plants (400 mg/kg). Conclusions: From the point of view of soil pollution with Mn, both examined sites can be considered suitable for production of healthy food. [ABSTRACT FROM AUTHOR]

Polychlorinated dibenzo- p -dioxins/dibenzofurans (PCDD/Fs), together with polycyclic aromatic hydrocarbons (PAHs), represent highly toxic and persistent organic environmental pollutants, especially due to their capability for bioaccumulation in fatty tissues. To observe the environmentally relevant effect of these compounds on earthworms, two soils naturally contaminated with PCDD/Fs and PAHs were used in our experiments. We focused on the role of CuZn- and Mn-superoxide dismutases. We assembled a full-length sequences of these molecules from Eisenia andrei earthworm and confirmed their activity. We demonstrated the significant reduction of CuZn-SOD on both mRNA and enzyme activity levels and increased levels of reactive oxygen species in earthworms kept in PCDD/F-polluted soil, which corresponds to the observed histopathologies of the earthworm intestinal wall and adjacent chloragogenous tissue. The results show an important role of CuZn-SOD in earthworm tissue damage caused by PCDD/Fs present in soil. We did not detect any significant changes in the mRNA expression or activity of Mn-SOD in these earthworms. In earthworms maintained in PAH-polluted soil the activity of both CuZn-SOD and Mn-SOD significantly increased. No histopathological changes were detected in these worms, however significant decrease of coelomocyte viability was observed. This reduced viability was most likely independent of oxidative stress. [ABSTRACT FROM AUTHOR]

This study investigated the effects of using chemical and organic fertilizer on arsenic (As), manganese (Mn), and cyanide (CN) absorption in tailings from a gold-mining tailing storage facility (TSF) by growing plants in a nursery. The experimental sets were prepared and classified into two sets: the first set used 15-15-15 chemical fertilizer, and the second set used organic fertilizer (manure). Two groups of plants were grown; the first group was comprised of monocot species, which were V. nemoralis and B. bambos, and the second group was comprised of dicot species, which were A. mangium and L. leucocephala. Plants and tailing samples were collected every 30 days during the six-month experiment. Growth was examined, and the absorption and accumulated amounts of As, Mn, and CN in the plant parts were analyzed. The findings showed that the accumulated amounts of As, Mn, and CN decreased when the experimental period increased. The accumulated amounts of As, Mn, and CN in the parts of experimental plants at 180 days indicated that V. nemoralis and A. mangium fertilized with chemical fertilizer (mass balance calculation) had higher rates of As, Mn, and CN absorption than those in the sets fertilized with organic fertilizer. V. nemoralis accumulated the most As and Mn in the underground part (roots), with values of 7.07 and 17.03 mg/kg, respectively, and absorbed the most CN in the aboveground part (shoots and leaves), with a value of 6.43 mg/kg. A. mangium absorbed the most As and Mn in leaves, with values of 5.64 and 40.51 mg/kg, respectively, and absorbed the most CN in shoots, with a value of 0.24 mg/kg. Therefore, it could be concluded that A. mangium (dicot species) and V. nemoralis (monocot species) had a high ability and potential to absorb toxicity or reduce the accumulated amounts of heavy metal. Furthermore, A. mangium and V. nemoralis would be suitable for application per relevant guidelines to solve the problem of As, Mn, and CN contaminated soil in other regions. [ABSTRACT FROM AUTHOR]

Leptospirosis is an important global public health problem. Favourable environmental factors are influencing the survival of leptospires in soil, which is an important link in the transmission cycle. The present study was designed to understand the correlation between various soil nutrients and presence of Leptospira in soil samples of different regions of Andaman and Nicobar Islands. The study revealed a significant positive relationship between presence of Leptospira and concentration of iron, manganese and copper in soil. Presence of iron, manganese and copper in the soil may influence the survival and transmission of leptospirosis. [ABSTRACT FROM AUTHOR]

Vegetation restoration is one of the most effective measures to restore degraded ecosystem in mining wasteland. A field experiment was conducted to study the effects of some site treatments’ three different approaches on the benefits of selective vegetation in the manganese mine. Three different approaches included (1) exposed tailings, the control treatment (tailing site); (2) soil covering of 10-cm thickness (external-soil site), and (3) soil covering of 10-cm thickness, soil ameliorating (adding fowl dung), and seeding propagation of Cynodon dactylon (Linn.) Pers. (rehabilitation site). The results indicated that 18 herb species were taken from 8 families and 4 woody plants in three sites after 1 year. After 3 years, 29 species from 14 families were observed in 3 sites. Meanwhile, compared with tailing site, the plant species of rehabilitation site was more than tailing site, and the plant abundance of external-soil site was similar to rehabilitation site. It was worthy to be mentioned that the plant species of external-soil site and rehabilitation site had a better effect on the plant community coverage of herb layer as compared with tailing site. In summary, the plant species of rehabilitation site had the most species diversity and could be recommended as the ve-restoration modes in manganese tail wasteland. [ABSTRACT FROM AUTHOR]

Numerous studies have associated air manganese (Mn) exposure with negative health effects, primarily neurotoxic disorders. This work presents a description of the emission and dispersion of PM 10 -bound Mn from industrial sources in the Santander bay area, Northern Spain. A detailed day-specific emission estimation was made and assessed for the main Mn source, a manganese alloy production plant under 8 different scenarios. Dispersion analysis of PM 10 -bound Mn was performed using the CALPUFF model. The model was validated from an observation dataset including 101 daily samples from four sites located in the vicinities of the manganese alloy plant. Model results were in reasonable agreement with observations ( r  = 0.37; NMSE = 2.08; Fractional Bias = 0.44 and Modelled/Observed ratio = 1.57). Simulated and observed Mn concentrations in the study area were much higher than the guidelines proposed by the World Health Organization (WHO) and the U.S. Environmental Protection Agency (USEPA), highlighting the need to reduce the Mn concentrations in the area. Based on the analysis of the Mn source contribution from the ferromanganese alloy plant, some preventive and corrective measures are discussed at the end of the paper. This work shows that CALPUFF dispersion model can be used to predict PM 10 -bound Mn concentrations with reasonable accuracy in the vicinities of industrial facilities allowing the exposure assessment of the nearby population, which can be used in future epidemiological studies. [ABSTRACT FROM AUTHOR]

Purpose: Understanding the status and dynamics of labile arsenic (As), iron (Fe), and manganese (Mn) across the sediment/water interface (SWI) is essential for As cycling in eutrophic lakes. This study conducted systematic monitoring of labile As, Fe, and Mn in water and sediments in regions of varying eutrophic levels in Lake Taihu to investigate Fe- or Mn-coupled cycling of As in sediments.Materials and methods: We arranged high-resolution combined ZrO-Chelex diffusive gradients in thin films (DGT) probes in intact sediment cores to measure labile As, Fe, and Mn (i.e., DGT-labile As, Fe, and Mn) under static condition for 24 h. After retrieval, we rinsed each probe first with lake water and then with deionized water to remove any visible sediment particles for analysis.Results and discussion: Results showed that DGT-labile As in overlying water and sediments was relatively higher in the middle or hyper-eutrophic regions compared to the mesotrophic region. Diffusive flux across the SWI further demonstrated that the internal dissolution of As in the middle or hyper-eutrophic region was stronger than the mesotrophic region, indicating that eutrophic environments may facilitate As release in sediments. We observed a positive correlation between DGT-labile As and Fe or Mn, which indicated that the reductive dissolution of As binding Fe/Mn oxyhydroxides in sediments was responsible for the internal release of As, which strengthens under eutrophic environments. Furthermore, the DGT-labile molar ratio of Fe/As or Mn/As had a significant positive relation with Fd, further confirming that labile Fe or Mn is much more relevant for sediment As cycling.Conclusions: Eutrophic environments facilitated reductive dissolution of As binding Fe/Mn oxyhydroxides in sediments, resulting in the release of more labile As in the middle or hyper-eutrophic region. [ABSTRACT FROM AUTHOR]

The aim of the current study was to identify major soil and leaf factors accounting for low natural rubber (NR, Hevea brasiliensis) productivity on tropical acid Acrisols in Vietnam. Twenty NR plots were measured with NR productivity, leaf factors (N, P, K, Ca, Mg, Mn, Cu, Fe, and Zn), soil factors (pH, particle size distribution, total C, N, P, K, exchangeable K, Ca, Mg, Al, Mn, Fe, Zn, available P). Cluster analysis showed that NR productivity could be separated into three clusters with low (23.2), medium (38.2), and high (61.3 g tree−1 harvest−1) yield. High-yield cluster had higher leaf P concentration and soil pH, while low-yield cluster had higher leaf Mn, soil exchangeable Al, and Mn concentration. Simple and multiple linear regression analysis applied with backward elimination procedure suggested that leaf and soil toxic concentration may be responsible for low NR productivity in the study soil. [ABSTRACT FROM AUTHOR]

Determination of copper (Cu), zinc (Zn) and manganese (Mn) micronutrients in soil samples have been studied for an efficient fertiliser application. Plant-available micronutrients of soils were extracted with DTPA extraction procedure, then differential pulse stripping voltammetry (DPSV) and square wave stripping voltammetry (SWSV) methods were performed with inexpensive and disposable pencil graphite electrode for determination of Cu(II), Zn(II) and Mn(II). Parameters such as deposition potential, deposition time, pH and concentration of the supporting electrolyte were optimised for these ions. Under optimised conditions, the limits of detection were found as 0.01 mg L-1 for Cu(II) and 0.02 mg L-1 for Zn(II) and 0.25 mg L-1 for Mn(II). Relative standard deviation (% RSD) was 6.80, 8.86 and 3.29 for Cu(II), Zn(II) and Mn(II), respectively. The experimental study was conducted using a flame atomic absorption spectroscopy. The described stripping voltammetry methods were successfully applied for the determination of Mn(II), Cu(II) and Zn(II) in soil samples. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A total of 74 samples of soil, sediment, industrial sludge, and surface water were collected in a Mediterranean estuarine system in order to assess the potential ecological impact of elevated concentrations of Co and Mn associated with a Terephthalic (PTA) and Isophthalic (PIPA) acids production plant. Samples were analyzed for elemental composition (37 elements), pH, redox potential, organic carbon, and CaCO3 content, and a group of 16 selected samples were additionally subjected to a Tessier sequential extraction. Co and Mn soil concentrations were significantly higher inside the industrial facility and around its perimeter than in background samples, and maximum dissolved Co and Mn concentrations were found in a creek near the plant’s discharge point, reaching values 17,700 and 156 times higher than their respective background concentrations. The ecological risk was evaluated as a function of Co and Mn fractionation and bioavailability which were controlled by the environmental conditions generated by the advance of seawater into the estuarine system during high tide. Co appeared to precipitate near the river mouth due to the pH increase produced by the influence of seawater intrusion, reaching hazardous concentrations in sediments. In terms of their bioavailability and the corresponding risk assessment code, both Co and Mn present sediment concentrations that result in medium to high ecological risk whereas water concentrations of both elements reach values that more than double their corresponding Secondary Acute Values. [ABSTRACT FROM AUTHOR]

Little is known about how Fe-Mn nodules vary in relation to pedogenetic horizons in soils derived from loess. In this investigation nodules were collected according to soil genetic horizons from a Fragiudalf in loess at Southeast Purdue Agricultural Center (SEPAC) in Indiana and physical, chemical, micro- and macromorphological features of nodules and their soil matrix were determined as a function of soil depth. The quantity, chemical composition, and micromorphology of the nodules varied with genetic horizons. The Ap horizon was found to contain the largest amount by weight of nodules (25.43 g/kg) and this was likely due to soil erosion. After the Ap horizon, the 2Btx1 and 2Btx2 horizons had the greatest content of Fe-Mn nodules by weight. Nodules had lower concentrations of SiO 2 , Al 2 O 3 , K 2 O, TiO 2 , MgO, Na 2 O, and CaO; in contrast Fe 2 O 3 , MnO, and P 2 O 5 in nodules showed clearly greater concentrations than that in the corresponding soil material. The SiO 2 content decreased with nodule size whereas Fe 2 O 3 and MnO increased. The least depletion of SiO 2 in nodules of 1–2 mm (N2) and 0.5–1 mm (N1) was in the Bt2 horizon, and was greatest in the 2Btx2. The Al 2 O 3 had accumulated in the N2 and N1 nodules within the Ap horizon and in the N2 within the 2Btx2 while other horizons were depleted of Al 2 O 3 . Brown nodules had a small Mn/Fe ratio (< 1), whereas black nodules had a large Mn/Fe ratio (> 1). The internal morphology of the nodules also varied with Mn/Fe ratios. The fungal hyphae or bacteria resulted in honeycomb, cell, cone, or dendritic structures. The cell and cone morphology required large Mn/Fe ratios, low pH, and high content of Al d . The scanning electron microscopy (SEM) analysis illustrated an elemental distribution trend such that the Mn was centralized in the nodule internal structure; whereas, Fe was concentrated towards the exterior. The band structure of nodules likely formed in response to seasonal wetting and drying as an accretionary process. Three basic formation stages for a well developed nodule can be inferred which correspond to different soil forming environments: 1) Fe enrichment for nucleus formation in wet soil, 2) Mn enrichment in an intense dry soil, and 3) Fe banding enrichment in a slightly dry soil. Nodule formation occurred synchronously with soil pedogenesis and can therefore be used as a proxy for understanding soil pedogenesis and the environment under which it occurred. [ABSTRACT FROM AUTHOR]

Natural concentrations of trace elements are necessary for assessing trace elements contamination affected by anthropogenic activities in soils. This study was conducted to establish background concentrations of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) in 50 unpolluted native soils with a total of 100 soil samples (surface and subsurface soil layers) in Hamedan province of Iran. Different methods have been used for the evaluation of background limits, and the relationships between soil properties and trace elements concentrations and among trace element concentrations have been analyzed. Values from Geometric Mean (GM) procedure had the lowest background limit, while the GM × GSD 2 (geometric standard deviation) method produces the highest background limits. The percentage of outliers in Median + 2MAD (median absolute deviation) ranged from 4.0 to 16.0% for natural data and from 0.0 to 12% for log-transformed data. The smallest outlier percentage was for Cd and Cr, and it was higher for Co, Cu, and Zn. The obtained geochemical baseline concentrations (mg kg −1 ) based on Median + 2MAD were (log-transformed data) Cd 1.36, Co 15.42, Cr (natural data) 36.69, Cu 29.99, Fe 25.79 (g kg −1 ), Mn 368.68, Ni (natural data) 53.59, Pb 39.60, Zn 103.80. Carbonate calcium had significant negative correlations with Co, Cr, Cu, Fe, and Mn, indicating that trace elements are not included in the crystal structure of secondary carbonate minerals; consequently, accumulation of CaCO 3 causes a dilution effect in the soils. The content of clay, silt and organic matter had significant role in the accumulation of Mn, Ni, and Pb in the soils of the studied area. Significant correlation was found among Co, Cr, Cu, Fe, Mn, and Ni and between Zn with Cd, Cr, Cu, Mn, and Ni. Factor analysis of trace elements explored six factors attributing 64.1% of the total variability. According to the results found by upper whisker method, correlation analysis and factor analysis, studied trace elements contaminated none of the soil samples, natural accumulation processes influenced their contents in soils and origin of trace elements may be lithogenic, but their sources may be different. [ABSTRACT FROM AUTHOR]

Manganese (Mn) deficiency limits wheat productivity on sandy loam, calcareous and alkaline soils cropped with rice. Variation of wheat genotypes to sustain production and Mn use from Mn deficient condition was investigated to screen efficient genotypes. Forty-seven diverse wheat genotypes were evaluated on Mn sufficient (0.195 µM) and Mn deficient (0 µM) nutrient solution to elucidate physiological basis of Mn deficiency tolerance and to develop manganese deficiency tolerance index (MDTI). Shoot dry weight and mean Mn accumulation was 136.7% and 76.5% enhanced when Mn nutrition was improved, respectively. Efficient genotypes under limited Mn had lower root length/shoot weight ratio but higher relative shoot growth rate with higher shoot demand on root which reflected higher Mn influx. Genotypes were classified as tolerant (>0.66), semi-tolerant (0.33–0.66) and sensitive (<0.33) on the basis of MDTI (0–1 scale). Manganese efficient genotypes are most desirable for sustainable production of wheat under low Mn. [ABSTRACT FROM PUBLISHER]

Reductive mobilization of arsenic (As) in paddy soils under flooded conditions is an important reason for the relatively high accumulation of As in rice, posing a risk to food safety and human health. The extent of As mobilization varies widely among paddy soils, but the reasons are not well understood. In this study, we investigated As mobilization in six As-contaminated paddy soils (total As ranging from 73 to 122 mg kg −1 ) in flooded incubation and pot experiments. Arsenic speciation in the solution and solid phases were determined. The magnitude of As mobilization into the porewater varied by > 100 times among the six soils. Porewater As concentration correlated closely with the concentration of oxalate-extractable As, suggesting that As associated with amorphous iron (oxyhydr)oxides represents the potentially mobilizable pool of As under flooded conditions. Soil containing a high level of manganese oxides showed the lowest As mobilization, likely because Mn oxides retard As mobilization by slowing down the drop of redox potential upon soil flooding and maintaining a higher arsenate to arsenite ratio in the solid and solution phases. Additions of a synthetic Mn oxide (hausmannite) to two paddy soils increased arsenite oxidation, decreased As mobilization into the porewater and decreased As concentrations in rice grain and straw. Consistent with previous studies using simplified model systems or pure mineral phases, the present study shows that Mn oxides and amorphous Fe (oxyhydr)oxides are important factors controlling reductive As mobilization in As-contaminated paddy soils. In addition, this study also suggests a potential mitigation strategy using exogenous Mn oxides to decrease As uptake by rice in paddy soils containing low levels of indigenous Mn oxides, although further work is needed to verify its efficacy and possible secondary effects under field conditions. [ABSTRACT FROM AUTHOR]

Copyright of Yuzuncu Yil Universitesi Journal of Agricultural Sciences (YYU J Agr Sci) is the property of Yuzuncu Yil University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aims: The restoration of vegetation in the rocky desertified areas of karst plateaus is a major problem for present-day ecological studies. The aim of this study was to determine the effects of vegetation restoration on the distribution and accumulation of trace elements in rhizosphere and non-rhizosphere soils. Methods: Four representative areas containing the plants Coriaria nepalensis Wall., Pinus armandii Franch., Elaeagnus pungens Thunb., and Cotoneaster hissaricus Pojark. were selected within a vegetation restoration area in the Karst Plateau of Caohai County, Guizhou Province, China. Soils were sampled using a grid method to measure the total contents of the trace elements iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in rhizosphere and non-rhizosphere soils. Results: The representative area containing Elaeagnus displayed the greatest amount of accumulation in the rhizosphere of both total and available trace elements, except for total Zn. Representative areas of the rhizosphere with other types of vegetation showed accumulation of only some of the trace elements studied. All types of vegetation were associated with the bioenrichment of available trace elements in both rhizosphere and non-rhizosphere soils, except for available Cu in areas associated with Cotoneaster. Conclusions: Representative areas containing Pinus displayed the greatest degree of bioenrichment for both total and available trace elements in both rhizosphere and non-rhizosphere soils. [ABSTRACT FROM AUTHOR]

The Great Salt Lake has been gradually desiccating, increasing the amount of exposed lakebed and potentially exposing heavy metals that may be present in the lakebed soil and sediments. It is hypothesized that there is a statistically significant difference between the current and previous shorelines, with the highest concentrations being at the current shoreline. This study used systematic sampling to collect 32 samples from the current shoreline and previous shorelines (elevation of 1281 and 1282 m, respectively) for a total of 64 samples. All samples underwent X-ray fluorescence analysis to quantify heavy metal concentrations. Nearly all samples contained arsenic (highest concentrations near the current shoreline). The majority of samples (80%) showed mercury levels below the limit of detection (LOD). A statistically significant difference in heavy metal concentrations between the two locations for arsenic, zinc, iron, manganese, rubidium, zirconium, and strontium was found. In addition, it was determined that the relationship between sample size (the number of values above the LOD) and location was statistically significant for mercury, selenium, lead, nickel, copper, manganese, zirconium, and thorium. Further research quantifying heavy metal concentrations in other parts of the Great Salt Lake and the potential for airborne exposures should be conducted. [ABSTRACT FROM PUBLISHER]

Reductive dissolution of soil manganese (Mn) oxides increases potential toxicity of Mn2+to plants. In order to examine the effect of nitrogen forms on reduction of Mn oxides in rhizosphere soil, a rhizobox experiment was employed to investigate the reduction of Mn oxides due to the growth of soybean and maize in an Oxisol with various contents of NO3–-N and NH4+-N and a total N of 200 mg kg−1. The results showed that exchangeable Mn2+in rhizosphere soil was 9.6–32.7 mg kg−1higher than that in bulk soil after cultivation of soybean and maize for 80 days, which suggested that plant root exudates increased reduction of soil Mn oxides. Application of ammonium-N promoted reduction of Mn oxides in rhizosphere soil compared to application of nitrate and nitrate together with ammonium. Soybean cultivation led to a higher reduction in soil Mn oxides than maize cultivation. Application of single ammonium enhanced Mn uptake by the plants and led to more Mn accumulating in plant leaves, especially for soybean. Therefore, application of ammonium-based fertilizer can promote reduction of soil Mn oxides, while application of nitrate-based fertilizer can inhibit reduction of soil Mn oxides and thus reduce Mn2+toxicity to plants. [ABSTRACT FROM AUTHOR]

The content of microelements and organic compounds in the soils of the former Semipalatinsk test nuclear polygon is investigated (STNP). It is found that the latter is characterized by a low content of copper, zinc, cobalt and an increased content of manganese. A minimum content of trace elements is observed in salt marshes and dark chestnut soils, while a maximum one is found in light-chestnut, meadow-chestnut and dark chestnut soils. The values of the heavy metals (Pb, Zn, Co, Cu, Ni) content in the soils of the polygon region suggest that STNP is a relatively dangerous area from a contamination point of view. The soil type does not affect the heavy metals content under normal and increased radionuclides background. This is also valid for the micronutrients present. It is concluded that STNP soils can be used for agricultural purposes. [ABSTRACT FROM AUTHOR]

The cost to dispose of sludge is very high, and Malaysia usually treats it by composting. However, composting is not a feasible method because it is time consuming. The application of sewage sludge on cropland is economical method because it provides the plant nutrients. However, it has a serious impact on the plants, animal and environment due to high concentration of heavy metals. Therefore, phytoremediation is a green technology to remove pollutants especially heavy metals from contaminated soil. This study was conducted to determine the potential of Ricinus communis to remove heavy metal in soil. The seedlings were planted on six different planting media T0 (100% soil-Control), T2 (80% soil + 20% sewage sludge), T3 (60% soil + 40 % sewage sludge), T4 (40% soil + 60% sewage sludge), T5 (20% soil + 80% sewage sludge) and T6 (100% sewage sludge). The highest accumulation of Mn was observed in leaves. Ricinus communis were found to be suitable as phytoremediators to clean heavy metals especially Mn as its TF value was higher than BCF. [ABSTRACT FROM AUTHOR]

We studied Fe-Mn concentric nodules from Cutanic Luvisol in the northern part of Namibia, where agricultural fields are irrigated with the drainage water from the Kombat Cu-Pb-(Zn) mine (pH 7, metal concentrations in μg l − 1 : Fe 7, Mn 10, Zn 7, Cu 18). Concentric nodules (0.5–2 cm in size) were mostly found towards the bottom of the sampled soil profile (Btcg2 horizon, depth 100–120 cm). Comparisons with the bulk chemical composition of the soil matrix showed that Fe-Mn nodules were enriched in metals, metalloids and other trace elements (with a few exceptions, enrichment factors varied in the range 1.3–6.4). The concentrations of the elements of interest in the Fe-Mn nodules were as follows (mg kg − 1 ): As 23.1, Ba 3840, Cd 6.83, Cu 450, Pb 597, Zn 137. The X-ray diffraction analysis indicated that the nodules were composed of quartz, goethite, hematite, illite/mica, pyrochroite, lithiophorite and birnessite. The scanning electron microscopy (SEM) observations confirmed that the internal structure of the nodules with concentric rings reflected seasonal changes in the redox conditions. Spot analyses and X-ray elemental maps performed using energy/wavelength dispersion spectrometry (EDS/WDS) showed that the concentrations of metalloids were rather low except for the slightly elevated Ba concentrations, which were observed only within the Mn oxide-rich zones. Selective extractions were used to understand the partitioning of trace elements within the individual phases. Whereas Mn oxides sequestered the majority of the Cd (up to 98%), Ba, Pb and rare earth elements (REEs) (up to 78%), other metals such as Cu and Zn exhibited much lower values (47–65%) and, together with oxyanionic species (As, Cr, V), were also significantly bound to Fe oxides. The pH-static leaching test conducted in the pH range 2–12 indicated that the majority of the trace elements were mostly leached under acidic conditions with the exception of As, which was highly solubilized at pH 12 (up to 17%). Whereas Ba, Cd, Cu and Zn were significantly released under acidic conditions (up to 12%), the leaching of Pb was almost negligible over the entire pH range. Our results show that Fe-Mn nodules act as significant traps for trace metals in Luvisols irrigated by mine water. However, an abrupt decrease in the pH and changes in the redox conditions may cause the dissolution of Fe-Mn nodules and subsequent release of contaminants into the soil system. [ABSTRACT FROM AUTHOR]

Rhizobium leguminosarum has two high-affinity Mn2+ transport systems encoded by sitABCD and mntH. In symbiosis, sitABCD and mntH were expressed throughout nodules and also strongly induced in Mn2+-limited cultures of free-living cells. Growth of a sitA mntH double mutant was severely reduced under Mn2+ limitation and sitA and mntH single mutants were more sensitive to oxidative stress. The double sitA mntH mutant of R. leguminosarum was unable to fix nitrogen (Fix-) with legumes belonging to the galegoid clade ( Pisum sativum, Vicia faba and Vicia hirsuta). The presence of infection thread-like structures and sparsely-packed plant cells in nodules suggest that bacteroid development was blocked, either at a late stage of infection thread progression or during bacteroid-release. In contrast, a double sitA mntH mutant was Fix+ on common bean ( Phaseoli vulgaris), a member of the phaseoloid clade of legumes, indicating a host-specific symbiotic requirement for Mn2+ transport. [ABSTRACT FROM AUTHOR]

Soil is a non-renewable resource, so it should be taken care of it. High quality food with sufficient yield for a growing human population can be produced only if plant nutrients are added to the soil by fertilizers to increase soil fertility, but the fertilizers have to be used economically, with the aim of raising the nutrient content available in the soil in order to meet plants' needs. The goal of the present investigation was to determine the effect of application of organic and mineral fertilizers as well as the effect of research environment on micronutrient content in red beet root. A field trial (2003-2005) was set up in a hilly part of Croatia according to the Latin square method, with four types of fertilization (control, 50 t stable manure*ha-1, 500 and 1,000 kg NPK 5-20-30*ha-1). After digestion of plant material with concentrated HNO3, iron, manganese, and zinc were determined by an atomic absorption spectrophotometer (AAS). The highest average red beet root micronutrient contents (270 mg Fe*kg-1 in dry matter, 96 mg Zn*kg-1 in dry matter, and 53 mg Mn*kg-1 in dry matter) were determined in the first research environment (Brašljevica in 2003) with low potassium soil content. There was a general decreasing trend in contents of the studied micronutrients (Fe, Mn and Zn) with NPK 5-20-30 fertilization (and by application of high doses of potassium), certainly due to antagonistic activity with potassium. It is suggested to fertilize with both 500 kg NPK 5-20-30*ha-1 and microelement fertilizers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Manganese-rich MnSAPO-34 molecular sieves were prepared by one-pot synthesis method for NO abatement using the ammonia-selective catalytic reduction (NH-SCR) technology and characterized using ICP, BET, XRD, FE-SEM, H-TPR, NH-TPD, XPS, and DR UV-Vis analyses. The experimental results indicate that the Mn content and chemical state, as well as the surface acidity, of the MnSAPO-34 molecular sieves significantly enhance their DeNO efficiency at low temperatures (ca. 200-300 °C). The manganese-rich MnSAPO-34 was synthesized using a combination of triethylamine and diisopropylamine as the structural directing agents and high Mn loading ( n(MnO)/ n(PO) = 0.4). The resulting catalyst exhibits the highest activity among all of the samples with a NO conversion value of nearly 95% and a N selectivity that is higher than 90% at 220-400 °C. In addition, this catalyst presents higher NO conversion than the conventional VO-WO/TiO catalysts and other SAPO-based catalysts below 300 °C. Furthermore, the analytical results indicate that the manganese species in the catalyst are mainly in the form of a framework Mn(IV), which could play a significant role in the NH-SCR process as the specific active species. The results suggest that controlling the types and content of the organic amine templates and variations in the surface acidity of the catalysts may significantly enhance the SCR activity at lower temperatures. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) has been applied to measure spectral characteristics and to perform quantitative analysis of the concentration of manganese in soil, an issue of great concern for precision agriculture. For the analysis, soil samples were compressed into pellets and a pulsed Nd:YAG laser was employed to produce the plasma in air at atmospheric pressure. Using this approach, we analyzed the time evolution of spectral characteristics and their dependence on the laser pulse energy. A calibration curve was constructed using reference sandy soil samples collected from a farm. An internal standard curve was used to improve the accuracy of the LIBS metrology for soil analyses. The results of this analysis demonstrated the usefulness of this method for analyzing the concentration of manganese in soil. [ABSTRACT FROM AUTHOR]

Manganese (Mn) cycling in the Critical Zone is important because of its role as an essential nutrient and potential toxicity to plants and organisms. Quantifying Mn enrichment in terrestrial environments has been limited since Mn is monoisotopic. However, elemental ratios of Mn/Ca ratios may be used to determine spatial Mn enrichment and in aboveground and belowground pools. The objectives of this study were to quantify the spatial variation in Mn concentrations and Mn/Ca ratios in foliage, bolewood, forest floor, and mineral soil horizons across the northeastern United States and compare Mn/Ca ratios to estimate enrichment. Forest floor and mineral soil samples were collected from 26 study sites across the northeastern United States and analyzed by strong acid digestion. Foliage and bolewood was collected from 12 of the 26 sites and analyzed for total Mn and Ca. Our results show forest floor and mineral soil horizon Mn concentrations and Mn/Ca ratios were higher at Pennsylvania and New York sites than New Hampshire and Vermont sites. Using a modified isotope equation, enrichment factors (EF) for Mn/Ca ratios were calculated to be ~ 3.6 in the forest floor, upper and lower mineral soil horizons at sites in New York and Pennsylvania compared to reference sites in New Hampshire and Vermont. Foliar and bolewood Mn concentrations also decreased from Pennsylvania towards New Hampshire. Moreover, foliar and bolewood Mn concentrations were strongly correlated to forest floor, upper, and lower mineral soil Mn concentrations. It was hypothesized that internal cycling (uptake, throughfall, and litterfall) of Mn controls retention of enriched Mn in forests. Geologic influences from a lithologic gradient and soil pH gradient could also influence Mn enrichment in addition to Mn pollution. Ratios of Mn/Ca and other elemental ratios hold promise as geochemical tracers but require further development. [ABSTRACT FROM AUTHOR]

The effect of liming on the availability of micronutrients to soybean cultivated during different numbers of years under no tillage (NT) was investigated. The treatments consisted of the number of years under NT (three, six, and nine years) and five rates of lime (0, 33, 67 and 100% of the amount calculated to raise soil base saturation to 70%) broadcast on soil surface plus the rate of 100% broadcast with incorporation in the 0-0.20 m layer of a clayey Red Oxisol. Soil and leaf samples were collected at two vegetative stages of the crop (vegetative V4 and blossoming R2). The soil was sampled at depths of 0-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m. Surface liming had little effect on extractable soil micronutrient and nutrient concentrations in soybean leaves. In the area with three years under NT, all liming rates decreased the extractable soil Zn up to a depth of 0.20 m. Lime incorporation decreased the extractable soil Mn in the surface layer. There were no differences in the extractable soil micronutrients and nutrient concentrations in soybean leaves as a function of the number of years under NT. These data suggest that broadcasting lime at current rates on soils under NT does not necessarily lead to micronutrient deficiencies. [ABSTRACT FROM AUTHOR]

This study was carried out to develop a process for recovering dissolved metals from acid mine drainages (AMD). AMD sludge normally consists of a heterogeneous mixture of many elements that are thrown out due to a lack of low purity. However, purified Fe, Al and Mn hydroxides would be potential resources. The AMD from Samma-Taejeong coal mine, Samcheok, Gangwon province in Korea was neutralized by adding neutralizing agents and oxidant, hydrogen peroxide to evaluate recovery of the metals and purity of their precipitates. The metals in AMD were recovered individually according to two process schemes: (i) only neutralization, and (ii) neutralization after addition of hydrogen peroxide. The result shows that using only neutralizing agents, both dissolved Al and Fe were concurrently precipitated around at pH 4.5 so that caused the purity of each precipitate to be lowered. In the case of oxidation and then neutralization of AMD, sequence of metal removal was Fe > Al > Mn in order. Recovery ratios of dissolved Fe and Al reached 99.2–99.3% at pH 4.5 and 70.4%–82.2% at pH 5.5, respectively. Recovery of Mn reached 37.8–87.5% at pH 8.5. Based on the results, oxidation before neutralization increased the recovery of dissolved Fe and Al in AMD with high purity of precipitates. [ABSTRACT FROM AUTHOR]

Abstract Forest floor carbon (C) sequestration has been negatively correlated with manganese (Mn) availability, possibly due to reduced efficacy of Mn-peridoxase enzymes produced by Agaricomycete fungi. I examined a soil C and Mn dataset from a podzolization gradient, along with fungal sporocarp Mn concentrations, to potentially corroborate this finding. An inverse power relationship between soil C and soil Mn content across temperate rainforests was confirmed, which provides further evidence of a Mn bottleneck in C turnover. Average Mn concentrations of saprotrophic sporocarps were greater than those of ectomycorrhizal fungi, and displayed a similar inverse correlation with increasing soil C. The absence or limited effectiveness of select saprotrophic fungi across Mn-depleted forest soils may be one mechanism behind impeded turnover of recalcitrant organic matter. Highlights • Corroboration of an inverse power correlation between forest soil C and exchangeable Mn. • Sporocarp Mn of saprotrophic fungi had a similar inverse correlation with increasing soil C. • Lack of key saprotrophic species as a possible cause in the impeded cycling of soil organic matter. [ABSTRACT FROM AUTHOR]

A surface-modified amorphous manganese oxide (SM-AMO) was prepared to increase the stability of a previously studied promising stabilizing agent and to compare its immobilizing efficiency with respect to contaminating metals with the original material. To synthesize the SM-AMO, the AMO surface was synthetically covered with a coating of MnCO 3 because newly formed rhodochrosite precipitates were previously found to increase the stability of AMO particles in soils. A preliminary experiment evaluating the long-term stability of both materials in pure water suggested higher stability for the SM-AMO particles, showing a smaller release of Mn compared to the original AMO. An adsorption kinetics study focused on As, Cd, Pb and Zn showed lower adsorption rates and adsorption capacity for Zn, probably as a result of partial surface passivation. In comparison to these results for simple controlled systems, different effects were recorded when the two materials were applied to contaminated soils. When incubated in soil, a constantly lower mass loss was recorded in the case of SM-AMO. There were no significant differences in the release of Mn and DOC into the soil solution or in the stabilizing efficiency with regard to contaminating metal(loid)s between the original and surface-modified materials. Concerning the potential solid phase transformations in soil conditions, we observed a gradual equilibration between the surface composition of both materials. While the newly formed rhodochrosite precipitated on the AMO surface, the MnCO 3 coatings on SM-AMO gradually dissolved. Both amendments also effectively supported microbial activity, especially in the more contaminated soil sample. Thus, despite the smaller mass loss, the effectiveness of both materials is comparable in the long term. [ABSTRACT FROM AUTHOR]

In this study a laboratory-scale slow sand filter (SSF) is used for removal of iron and manganese and the effects of various inlet concentrations on removal efficiency were investigated. SSF was operated at a filtration rate of 0.2 m.h-1 with two different synthetic inlet waters (Run1 and Run2). Iron and manganese concentrations in two runs were 1.09±0.13mg.L-1-1.06±0.10 mg.L-1 for Run1 and 2.02±0.15 mg.L-1- 2.10±0.14 mg.L-1 for Run2. In Run1, the removal efficiencies of 96.3±2.48%, 92.3±6.1%, 92.6±5.7%, and 55.3±8.3% were obtained for turbidity, iron, manganese and total organic carbon (TOC), respectively. In Run2, on the other hand, the removal efficiencies were obtained as 97.9±1.3%, 93.1±8.1%, 94.4±5.8%, and 55.5±6.8%, respectively. Results suggested that the SSF was the most efficient in turbidity removal at a filtration rate of 0.2 m.h-1. Sequence analyses of DGGE bands from Run1 and Run2 were also performed and results indicated that a range of bacteria were present, with 16S rRNA gene sequences similar to groups such as Gallionella, Leptothrix, Crenothrix, and an uncharacterized environmental clone. [ABSTRACT FROM AUTHOR]

Chemical forms of Mn and Zn in the soil and its availability to soybeans grown in a Latosol for 12 years under different tillage systems were studied. The effects of these systems on Mn complexation by soil humic acid (HA) were also evaluated. The field experiment was carried out in a randomized block (three blocks) split-plot experimental design. The main treatments consisted of four tillage systems and the secondary, of three soil sampling depths (0.00–0.05 m, 0.05–0.10 m and 0.10–0.20 m). The tillage systems were no tillage (NT), conventional tillage (CT), minimum tillage (MT) and NT with scarification, every three years. The results presented refers to the last 2 years of the experiment, 2000 and 2001. In average numbers, the Zn content of the 0.00–0.05 m layer was lower in soil under CT (2 mg kg −1 ), compared to the other tillage systems (NT and NT with scarification = 2.7 and MT = 2.8 mg kg −1 ). In general, Zn percentages in exchangeable, organic, oxides and residual forms were not modified by the tillage systems. In turn, the Mn content of the soil surface layer under the NT was higher than in the soil under CT. Mn contents extracted with DTPA were 11 and 5.2 mg kg −1 in the soil under NT and CT, respectively. The Mn contents extracted with Mehlich I, Mehlich III and HCl in the soil under CT were 20.8, 8.7 and 16.8 mg kg −1 , respectively. In the soil under NT, the contents extracted with the same extractors were 27.9, 15 and 29.2 mg kg −1 . In the surface layer, higher Mn percentages in the organic fraction were found in the soil under NT (19.2%) and NT with scarification (15.9%) than in soil under CT (11.8%). The Mn content of this layer was also positively correlated with the soil organic matter, but none of the extractors used (DTPA-TEA pH 7.3, HCl 0.1 mol L −1 , Mehlich I and III) properly assessed the levels of Mn and Zn available to plants, suggesting the need for further studies. It was not observed presence of Mn in the HA samples by electron paramagnetic resonance (EPR). Since the digestion by nitro-perchloric acid of the HA samples showed the presence of Mn in these samples, it strengthens the hypothesis that Mn was bound to the HA in the form of stable complexes (covalent bonds), since this form of Mn cannot be detected by EPR. During soybean cultivation, Mn concentrations in the leaves did not vary with the tillage methods and were near or below the range considered adequate for the crop. Furthermore, visual symptoms of Mn deficiency in the leaves were observed in the initial stages of plant development, regardless of treatment. This suggests the need for new correlation and calibration studies for micronutrients in Brazil, especially for soils cultivated under the NT. [ABSTRACT FROM AUTHOR]

In order to study the effect of Tehran municipal solid wastes compost on manganese accumulation in soil and to determine its concentration in any readily available plant forms (exchangeable and carbonates-bonded), Mn-oxides bonded fraction, organic matter bonded fraction, and residual fraction in a calcareous soil, a factorial experiment based on completely randomized block design (RCBD) was conducted in research field of Shahed university at different levels of municipal solid wastes compost (0, 15, 30, and 60 ton/ha) as first factor and application times (one- or two-year compost application) as second factor in three replications. Results showed that, by increasing compost level, total Mn concentration, DTPA-extractable concentration, and amounts existing in all five fractions were increased, so lowest and highest amounts of Mn were observed in control and 60 ton/ha compost application. Based on results from Mn fractionation using Tessier consecutive extraction method, Mn fractions in all samples were in the following order: residual > Fe-Mn oxides > carbonates-bonded > organic matter-bonded ≫ exchangeable fractions in which residual fraction (RE) at first and second year was dominant rather than other fractions by 34.28–43.04 and 34.28–49.48 percent, respectively. Mn concentration in Fe-Mn oxides-bonded fraction at both years was considerable. Mn amounts in Fe-Mn oxides- bonded, application times were decreased. [ABSTRACT FROM AUTHOR]

Background: Manganese (Mn) has several essential functions in plants, including a role as cofactor in the oxygen evolving complex (OEC) of photosystem II (PSII). Manganese deficiency is a major plant nutritional disorder in winter cereals resulting in significant yield reductions and winter kill in more severe cases. Among the winter cereals, genotypes of winter barley are known to differ considerably in tolerance to Mn deficiency, but the genes controlling the Mn deficiency trait remains elusive. Results: Experiments were conducted using 248 barley varieties, cultivated in six distinct environments prone to induce Mn deficiency. High-throughput phenotyping for Mn deficiency was performed by chlorophyll a (Chl a) fluorescence analysis to quantify the quantum yield efficiency of PSII. High-throughput phenotyping in combination with ICP-OES based multi-element analyses allowed detection of marker-trait associations by genome wide association (GWA) mapping. Several key candidate genes were identified, including PSII subunit proteins, germin like proteins and Mn superoxide dismutase. The putative roles of the encoded proteins in Mn dependent metabolic processes are discussed. Conclusions: Fifty-four candidate genes were identified by Chl a fluorescence phenotyping and association genetics. Tolerance of plants to Mn deficiency, which is referred to as Mn efficiency, appeared to be a complex trait involving many genes. Moreover, the trait appeared to be highly dependent on the environmental conditions in field. This study provides the basis for an improved understanding of the parameters influencing Mn efficiency and is valuable in future plant breeding aiming at producing new varieties with improved tolerance to cultivation in soil prone to induce Mn deficiency. [ABSTRACT FROM AUTHOR]

High concentrations of iron (Fe(II)) and manganese (Mn(II)) reductively dissolved from soil minerals have been detected in groundwater monitoring wells near many municipal solid waste landfills. Two in situ permeable reactive barriers (PRBs), comprised of limestone and crushed concrete, were installed downgradient of a closed, unlined landfill in Florida, USA, to remediate groundwater containing high concentrations of these metals. Influent groundwater to the PRBs contained mean Fe and Mn concentrations of approximately 30 mg/L and 1.62 mg/L, respectively. PRBs were constructed in the shallow aquifer (maximum depth 4.6 m below land surface) and groundwater was sampled from a network of nearby monitoring wells to evaluate barrier performance in removing these metals. PRBs significantly ( p < 0.05) removed dissolved Fe and Mn from influent groundwater; Fe was removed from influent water at average rates of 91% and 95% (by mass) for the limestone and crushed concrete PRBs, respectively, during the first year of the study. The performance of the PRBs declined after 3 years of operation, with Fe removal efficiency decreasing to 64% and 61% for limestone and concrete PRBs, respectively. A comparison of water quality in shallow and deep monitoring wells showed a more dramatic performance reduction in the deeper section of the concrete PRB, which was attributed to an influx of sediment into the barrier and settling of particulates from the upper portions of the PRBs. Although removal of Fe and Mn from redox impacts was achieved with the PRBs, the short time frame of effectiveness relative to the duration of a full-scale remediation effort may limit the applicability of these systems at some landfills because of the construction costs required. [ABSTRACT FROM AUTHOR]

By-products of animal breeding and raising can contain considerable amounts of trace elements, including Mn and Fe, due to the fact that their amounts in fodders are purposefully being increased. Thermal conversion of pig manure and poultry litter may have a significant effect on changes in the content and mobility of Mn and Fe in these materials. The aim of the research was to evaluate the effect of thermal conversion of pig manure and poultry litter on the content and mobility of Mn and Fe in biochars and in soil after their application (0.5%, 1%, and 2% amendments to the soil). As a result of thermal conversion of pig manure and poultry litter, an increase in the content of total forms and a reduction of Mn and Fe forms extracted with water were recorded. The 2% amendment of pig manure biochar to soil caused an increase in the content of mobile forms of Fe, whereas poultry litter biochar decreased mobility of this element. Introduction of pig manure biochar and poultry litter biochar to the soil caused a similar immobilization of mobile forms of Mn as in the case of application of thermally unprocessed manure and litter. It has been shown that the content of Fe and Mn extracted with 0.025 M C10H22N4O8 was higher than the content of these elements extracted with 1 M NH4NO3. [ABSTRACT FROM AUTHOR]

The concentration of manganese was determined in wastewater, soil and vegetable (carrot, lettuce, onion, spinach, cabbage, tomato and okro) samples that were collected on seasonal basis from January, 2013 to September 2014 along Kubanni stream channels in Zaria using Atomic Absorption Spectrophotometer. The results showed manganese levels in wastewater were in the range of 5.00 -20.04 mg/L for the year 2013 and 1.08 - 5.50 mg/L in 2014; 2.10 - 15.30 mg/Kg for the year 2013 and 3.42 - 13.57 mg/Kg in 2014 for the soil while the vegetables had concentrations in the range of 4.39 - 15.04 mg/Kg for the year 2013 and 0.10 - 13.42 mg/Kg in 2014. Statistical analysis revealed no significant difference in manganese levels across the locations and seasons for wastewater, soil and vegetables analyzed at p = 0.050. Pearson correlation showed negligible (r = 0.166) relationship between manganese levels in wastewater for the year 2013 and 2014, moderate (r = 0.479) relationship was also obtained for the soil between these tivo years likewise, moderate (r = 0.457) relationship was obtained for vegetables cultivated in 2013 and that of 2014 respectively. Manganese concentrations obtained in this study ivas higher than Maximum Contaminant Levels set by Standard Organizations such as W.H.O. and F.A.O for wastewater while both soil and vegetables were within the limits set by these bodies. [ABSTRACT FROM AUTHOR]

An amorphous Mn oxide (AMO), nanomaghemite, and nanomagnetite were used as potential amendments reducing the mobility of As in three contrasting contaminated soils differing in origin of As contamination. Adsorption experiments and XPS analyses combined with incubation batch experiments and pH-static leaching tests were used. The AMO showed excellent adsorption capacity for As(V) reaching a maximum of 1.79 mmol g at pH 7 and 8. Interestingly, the adsorption capacity in this case decreases with decreasing pH, probably as a result of AMO dissolution at lower pH values. Chemical sorption of As(V) onto AMO was further confirmed with XPS. Both Fe nano-oxides proved the highest adsorption capacity at pH 4 reaching 11 mg g of adsorbed As(V). The AMO was also the most efficient amendment for decreasing As concentrations in soil solutions during 8 weeks of incubation. Additionally, pH-static leaching tests were performed at pH 4, 5, 6, 7, and natural pH (not adjusted) and AMO again proved the highest ability to decrease As content in leachate. On the other hand, strong dissolution of this amendment at lower pH values (especially pH 4) was observed. For that reason, AMO appears as a promising stabilizing agent for As, especially in neutral, alkaline, or slightly acidic soils, where As(V) species are expected to be more mobile. [ABSTRACT FROM AUTHOR]

The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems. [ABSTRACT FROM AUTHOR]