Mobilization, release and speciation of arsenic in an As-contaminated gold mine spoil under varied soil redox conditions

2020 ◽  
Author(s):  
Albert Kobina Mensah ◽  
Bernd Marschner ◽  
Jianxu Wang ◽  
Sabry M. Shaheen ◽  
Jörg Rinklebe
Keyword(s):  
Extraction Procedure ◽  
Mineralogical Composition ◽  
Redox Conditions ◽  
Mine Spoil ◽  
Residual Fraction ◽  
Reductive Dissolution ◽  
Gold Mine ◽  
Soil Redox ◽  
Reducing Conditions ◽  
The Impact

<p>Redox-induced release dynamics of arsenic (As) in an abandoned geogenic arsenic-contaminated gold mine spoil in Ghana has never been studied. Therefore, our aim was to investigate the effects of varied soil redox conditions on mobilisation and speciation of As from an abandoned highly contaminated gold mine spoil (with 4,283 mg As/kg soil) using an automated biogeochemical microcosm set-up. We also studied the impact of redox potential (E<sub>H</sub>)-dependent changes of pH, Fe, Mn, Al, S, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, DOC, DIC, DC, DN and SUVA on the release dynamics of As. As mineralogical composition and speciation were further determined using a synchrotron-based X-ray absorption spectroscopy (XANES). Linear combination fits of XANES results indicated that scorodite (FeAsSO<sub>4</sub>) and arsenopyrite (FeAsS) are the two major As-containing minerals in the studied mine spoil. Geochemical fractionation using sequential extraction procedure indicated greater proportions of the extracted As in the amorphous iron oxide fraction III (1390.13 mg kg<sup>-1</sup>, 32.5% of the total As) and residual fraction V (2591.67 mg kg<sup>-1</sup>, 60.5% of the total As). Concentrations of dissolved Fe and SUVA were higher during reducing conditions and decreased under oxidising conditions and both showed negative significant relationships with E<sub>H</sub> (E<sub>H </sub>and SUVA: r = -0.76, <em>P <</em> 0.01; E<sub>H</sub> and Fe: r = -0.75). Mobilisation of As was greater under reducing conditions (dissolved As = 136.68 mg/L) than in oxidising environments (dissolved As = 8.06 mg/L). The release of As under low E<sub>H</sub> can be explained by the associated reductive dissolution of Fe oxides, as demonstrated by the high positive significant relationship between Fe and As (r = +0.97, <em>P <</em> 0.01). Dissolved As release dynamics can also be linked to desorption of aromatic carbon compounds on the surfaces of dissolved organic carbon, as demonstrated by the high positive significant correlation between SUVA and As (r = +0.573, <em>P <</em> 0.01). Further, the release dynamics of dissolved As was also affected by changes in pH (r = -0.4, <em>P <</em> 0.05), but were not affected by redox-induced dynamics of Mn, Al, S, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, DOC, DIC, DC, DN. We conclude that conditions such as flooding and high rainfall in this contaminated mine spoil could create reducing conditions, leading to reductive dissolution of the arsenopyrite As-bearing primary mineral and may lead to higher As release into the groundwater, translocation into the food chain with potential impacts on human health.</p><p><strong>Keywords</strong>: Arsenopyrite, redox chemistry, arsenic mobilisation, gold mine spoil, reductive and oxidative dissolution.</p>

Waterlogging and soil reduction affect the amount and apparent molecular weight distribution of dissolved organic matter in wetland soil: a laboratory study

Soil Research ◽  
2018 ◽  
Vol 56 (1) ◽  
pp. 28 ◽  
Author(s):  
Asmaa Rouwane ◽  
Malgorzata Grybos ◽  
Isabelle Bourven ◽  
Marion Rabiet ◽  
Gilles Guibaud
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Humic Substances ◽  
Apparent Molecular Weight ◽  
Redox Condition ◽  
Redox Conditions ◽  
Wetland Soil ◽  
Soil Redox ◽  
Reducing Conditions

The release of dissolved organic matter (DOM) from wetland soils is an important pathway for the input of organic compounds into adjacent aquatic environments. In the present study we investigated, under controlled laboratory conditions, the quantity and quality of DOM released from a wetland soil subject to waterlogging and reducing conditions. Three soil redox conditions (oxic, moderately reducing and advanced reducing) were distinguished based on nitrate, ferrous ions and sulfate concentrations in soil solution. Under each redox condition, the quantity (dissolved organic carbon (DOC), humic substances and peptides plus proteins (P-PN) and quality (aromaticity; specific ultraviolet absorbance at 254 nm (SUVA254nm)) and apparent molecular weight (aMW) distribution) of DOM were investigated. The results showed that soil redox condition affects the amount and properties of mobilised DOM. The rate of DOM release and SUVA254 values were highest during the transition from oxic to moderately reducing conditions, whereas both stabilised during progression to advanced reducing conditions. In addition, the mobilised DOM is expected to be more reactive because of an increase in polar substituents in aromatic structures between oxic and moderately reducing conditions. During the development of moderately reducing conditions, dissolved humic substances increased significantly, whereas their aMW distribution (between 500 and 6000 ) remained constant for each of the three different redox conditions. In contrast, the quantity of dissolved P-PN remained low and steady under the three redox conditions, whereas the aMW distribution of protein-like and microbial by-product-like compounds decreased during the development of reducing conditions (aMW of compounds between 100 and >100 000).

Metallic pollution in clogging materials of urban porous pavements

1995 ◽  
Vol 32 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Valérie Colandini ◽  
Michel Legret ◽  
Yves Brosseaud ◽  
Jean-Daniel Baladès
Keyword(s):  
Heavy Metal ◽  
Particle Size ◽  
Road Traffic ◽  
Total Concentration ◽  
Extraction Procedure ◽  
Interaction Strength ◽  
Metal Mobility ◽  
Residual Fraction ◽  
Metal Contents ◽  
Copper Zinc

Porous pavements infiltrated with stormwater are faced with clogging problems: runoff particles seep and clog the pervious surface layer of these structures. Clogging material samples (in the form of sludge) have been collected in cleaning operations on the pervious asphalt. This study aims at characterizing these materials, particle size distribution, heavy metal contents by particle size, and studying interactions between metals and particles. A sequential extraction procedure proposed by the experts of the Community Bureau of Reference (B.C.R.) was applied to provide information about heavy metal distribution on particles and to evaluate interaction strength, and consequently potential metal mobility when chemical variations occurred in the environment. Mainly made up of sand, the materials are polluted with lead, copper, zinc and cadmium. The concentrations appeared to be linked with road traffic intensity. The heavy metal contents by particle size showed that the finer are the particles, the higher are the heavy metal concentrations. Heavy metals were found potentially labile; metals contents in the residual fraction (mineral fraction) represented less than 20 % of the total concentration. Cadmium and zinc were apparently more labile than lead and copper.

scholarly journals Chemical Speciation and Potential Mobility of Heavy Metals in the Soil of Former Tin Mining Catchment

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
M. A. Ashraf ◽  
M. J. Maah ◽  
I. Yusoff
Keyword(s):  
Chemical Speciation ◽  
Extraction Procedure ◽  
Optical Emission ◽  
Residual Fraction ◽  
Emission Spectrometry ◽  
Trophic Chain ◽  
Toxic Risk ◽  
Mobile Forms ◽  
Average Potential ◽  
Potential Mobility

This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.

Aberrant activation of complement system in renal grafts is mediated by cold storage

2021 ◽  
Author(s):  
Sorena Lo ◽  
Li Jiang ◽  
Savannah Stacks ◽  
Haixia Lin ◽  
Nirmala Parajuli
Keyword(s):  
Cold Storage ◽  
Complement System ◽  
Complement Activation ◽  
Renal Tubules ◽  
Renal Transplants ◽  
Reducing Conditions ◽  
Tnf Α ◽  
Renal Grafts ◽  
The Impact ◽  
The Complement System

Aberrant complement activation leads to tissue damage during kidney transplantation, and it is recognized as an important target for therapeutic intervention (6, 19, 35, 64). However, it is not clear whether cold storage (CS) triggers the complement pathway in transplanted kidneys. The goal of this study was to determine the impact of CS on complement activation in renal transplants. Male Lewis and Fischer rats were used, and donor rat kidneys were exposed to 4 h or 18 h of CS followed by transplantation (CS+Transplant). To study CS-induced effects, a group with no CS was included in which the kidney was removed and transplanted back to the same rat (autotransplantation, ATx). Complement proteins (C3 and C5b-9) were evaluated with western blotting (reducing and non-reducing conditions) and immunostaining. Western blot of renal extracts or serum indicated that the levels of C3 and C5b-9 increased after CS+Transplant compared to ATx. Quite strikingly, intracellular C3 was profoundly elevated within renal tubules after CS+Transplant but was absent in Sham or ATx groups, which showed only extratubular C3. Similarly, C5b-9 immunofluorescence staining of renal sections showed an increase in C5b-9 deposits in kidneys after CS+Transplant. Real-time PCR (SYBR Green) showed increased expression of CD11b and CD11c, components of complement receptors 3 and 4, respectively, as well as inflammatory markers such as TNF-α. In addition, recombinant TNF-α significantly increased C3 levels in renal cells. Collectively, these results demonstrate that CS activates the complement system in renal transplants.

scholarly journals Physico-chemical variability and heavy metal pollution of surface sediment in a non-channeled section of Dilúvio Stream (Southern Brazil) and the influence of channeled section in sediment pollution

2019 ◽  
Vol 14 (1) ◽  
pp. 1 ◽  
Author(s):  
Pedro Alexandre Sodrzeieski ◽  
Leonardo Capeleto de Andrade ◽  
Tales Tiecher ◽  
Flávio Anastácio de Oliveira Camargo
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Total Concentration ◽  
Mineralogical Composition ◽  
Sediment Pollution ◽  
Anthropogenic Influence ◽  
Southern Brazil ◽  
Physico Chemical ◽  
Chemical Variability ◽  
The Impact

Dilúvio Stream flows through an area with a great population density in Porto Alegre, Southern Brazil. The anthropogenic influence in the surroundings impacted negatively the quality of the sediments of Dilúvio Stream and Lake Guaíba. This study evaluated the physico-chemical variability of surface sediments in a non-channeled section of Dilúvio Stream. Additionally, we compared the concentration of several heavy metals in this section with data from previous studies in the margins of Lake Guaíba near the outflow of Dilúvio Stream in order to evaluate the impact of urbanization on sediment pollution. The pH, bulk density, particle-size distribution, electrical conductivity, organic carbon, assimilable phosphorus, total nitrogen, mineralogical composition (X-ray diffractogram) and pseudo total concentration of several metals (Fe, Al, Ca, Mg, Na, K, Mn, Ba, Zn, V, As, Pb, Cu, Cr, Co, Ni, Cd, Mo, and Se) were evaluated. The results showed that the sediments in the non-channeled section of Dilúvio Stream are predominantly sandy, with heavy metal contents below the quality reference values. Quartz and feldspar predominated in all sites. The concentration of Zn, Pb, Cu, Cr, and Ni were lower than that observed in the margins of Lake Guaíba near the outflow of Dilúvio Stream, possibly due to pollution input throughout the channeled section. The Dilúvio Stream shows indications of an anthropogenic influence in the heavy metals concentration through the channeled area.

Geochemical Behaviour of Uranium in Sedimentary Formations: Insights From a Natural Analogue Study

2009 ◽  
Author(s):  
Ulrich Noseck ◽  
Vaclava Havlova ◽  
Juhani Suksi ◽  
Thomas Brasser ◽  
Radek Cervinka
Keyword(s):  
Current Knowledge ◽  
Natural Analogue ◽  
Near Surface ◽  
Co2 Partial Pressure ◽  
Long Term Stability ◽  
Reducing Conditions ◽  
Phosphate Mineral ◽  
Sedimentary System ◽  
The Impact

Groundwater data from the natural analogue site Ruprechtov have been evaluated with special emphasis on the uranium behaviour in the so-called uranium-rich clay/lignite horizon. In this horizon in-situ Eh-values in the range of −160 to −280 mV seem to be determined by the SO42−/HS− couple. Under these conditions U(IV) is expected to be the preferential redox state in solution. However, on-site measurements in groundwater from the clay/lignite horizon show only a fraction of about 20% occurring in the reduced state U(IV). Thermodynamic calculations reveal that the high CO2 partial pressure in the clay/lignite horizon can stabilise hexavalent uranium, which explains the occurrence of U(VI). The calculations also indicate that the low uranium concentrations in the range between 0.2 and 2.1μg/l are controlled by amorphous UO2 and/or the U(IV) phosphate mineral ningyoite. This confirms the findings from previous work that the uranium (IV) mineral phases are long-term stable under the reducing conditions in the clay/lignite horizon without any signatures for uranium mobilisation. It supports the current knowledge of the geological development of the site and is also another important indication for the long-term stability of the sedimentary system itself, namely of the reducing geochemical conditions in the near-surface (30m to 60 m deep) clay/lignite horizon. Further work with respect to the impact of changes in redox conditions on the uranium speciation is on the way.

scholarly journals Ferrosilicate glass ceramics based on wastes from ore concentration

2021 ◽  
pp. 95-103
Keyword(s):  
Surface Layer ◽  
Iron Ore ◽  
Glass Ceramics ◽  
Redox Conditions ◽  
Glass Technology ◽  
Crystalline Phases ◽  
Reducing Conditions ◽  
Deep Layers ◽  
Hematite Fe2o3 ◽  
Crystallization Of Glass

We showed in this work that there is a possibility of recycling the wastes derived from iron ore concentration by using glass technology. The compositions of new glass ceramics with high technological and decorative properties were developed. The influence of Al2O3, MgO and Na2O additives to the waste from ore benefication on the parameters of the synthesized glass and its crystallization products was studied. The optimal temperatures of synthesis, annealing and crystallization of glass samples in the systems (Fe2O3–FeO)–SiO2–Al2O3–Na2O and (Fe2O3–FeO)–SiO2–Al2O3–MgO were shown to be 1450100С, 500–6000С and 700–8000C, respectively. It was established that the redox conditions of crystallization of glasses in the system (FeO–Fe2O3)–SiO2–Al2O3–Na2O strongly affect the nature of the iron-containing phases that are formed: oxidative conditions favors the formation of hematite (Fe2O3) and aegirinite (Na2OFe2O34SiO2), whereas reducing conditions contributes to the formation of wustite (FeO) and fayalite (2FeOSiO2). In the system (FeO–Fe2O3)–SiO2–Al2O3–MgO under both oxidative and reducing conditions of crystallization, the same crystalline phases appear: olivine (2(Mg,Fe)OSiO2), hercin (FeOAl2O3) and iron metasilicate (FeOSiO2). It was shown that the crystallization of samples under reducing conditions allows producing materials with higher microhardness. The surface layer of glasses and glass ceramics exhibited less microhardness than their deep layers.

scholarly journals Methodological study of extraction procedures applied to urban particulate matter

2011 ◽  
Vol 9 (6) ◽  
pp. 1071-1079 ◽  
Author(s):  
Jirina Sysalova ◽  
Jirina Szakova ◽  
Walter Goessler ◽  
Jana Tremlova
Keyword(s):  
Extraction Procedure ◽  
Arsenic Species ◽  
Water Soluble ◽  
Icp Oes ◽  
Methodological Study ◽  
Species Occurrence ◽  
Air Filters ◽  
Extraction Procedures ◽  
Icp Ms ◽  
The Impact

AbstractThe modified BCR three-step sequential extraction procedure has been applied to two different samples of urban particulate matters (PM). The distribution of selected trace elements As, Cd, Cr, Mn, Ni, Pb, Zn was investigated and, in a comparative study, the presence of common organic air filters in extraction procedures was evaluated. Analytes in separate fractions were determined by ICP-OES and GFAAS, respectively, depending on concentration levels. While, due to air filters, a significant increase of some analytes mobility in individual fractions has been observed in case of the jet-milled PM (tunnel Letna), but in case of the PKC sample such effect was not found. The analyte impurities built in some filters has been tested, and the impact on the reliability of analyte results has been discussed. The arsenic species occurrence and their stability in presence of air filters (size 47 mm) were investigated in both urban PM samples as well, using HPLC-ICP-MS technique. Water soluble and by three-step BCR procedure extractable arsenic forms are shown in chromatograms

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