scholarly journals The Role of Barite in the Post-Mining Stabilization of Radium-226: A Modeling Contribution for Sequential Extractions

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 497 ◽  
Author(s):  
Clémence Besançon ◽  
Camille Chautard ◽  
Catherine Beaucaire ◽  
Sébastien Savoye ◽  
Paul Sardini ◽  
...  
Keyword(s):  
Sequential Extraction ◽  
Mine Tailings ◽  
Sequential Extractions ◽  
Iron Oxyhydroxides ◽  
Retention Capacity ◽  
Geochemical Behavior ◽  
Mill Tailings ◽  
Binding Phase ◽  
Direct Interpretation

Barite is ubiquitous and known to incorporate 226Ra through the formation of a solid-solution. In U mining mill tailings, barite is one of the dominant sulfate-binding minerals. In such environments, sequential extractions are generally used to identify the U- and 226Ra-binding phases and their associated reactivity. To better decipher the main processes governing the behavior of 226Ra during such sequential extractions, a geochemical model was developed with PHREEQC mimicking the sequential extraction of U and 226Ra from Bois-Noirs Limouzat U mine tailings, France. The model results were compared with a dataset produced by an experimental sequential extraction from the same mine tailings and including data on the solids and selective extraction results with the major elements, U and 226Ra. The simulations reproduced the results of the experimental chemical extractions accurately, with iron oxyhydroxides being the major U binding phase. However, the modeling indicated rather that barite would be the main 226Ra binding phase, instead of the iron oxyhydroxides identified by the experimental extractions. This is consistent with the 226Ra concentration measured in pore water, but in disagreement with the direct interpretation of the sequential extractions. The direct interpretation disregarded the role of barite in the geochemical behavior of 226Ra because barite was not specifically targeted by any of the extraction steps. However, the modeling showed that the dissolution of 226Ra-binding barite by reactants would lead to a 226Ra redistribution among the clay minerals, resulting in a skew in the experimental results. Similar results were achieved by referring simply to the bulk mineralogy of the tailings. This study highlights the importance of considering the mineralogy, mineral reactivity and retention capacity for more realistic interpretation of sequential extractions. Moreover, this paper provides new perspectives on the long-term consequences of these mill tailings in which barite controls the geochemical behavior of the 226Ra.

The role of nanoscale aggregation of ferrihydrite and amorphous silica in the natural attenuation of contaminant metals at mill tailings sites

2021 ◽  
Vol 298 ◽  
pp. 207-226
Author(s):  
Keisuke Kawamoto ◽  
Hiroki Yokoo ◽  
Asumi Ochiai ◽  
Yuriko Nakano ◽  
Ayaka Takeda ◽  
...  
Keyword(s):  
Amorphous Silica ◽  
Natural Attenuation ◽  
Mill Tailings ◽  
Contaminant Metals

scholarly journals Application of a Sequential Extraction Method for Analyzing Cu Distribution in Pre-Treated Mine Tailings after Electrodialytic Remediation

2019 ◽  
Vol 16 (4) ◽  
pp. 584 ◽  
Author(s):  
Andrea Lazo ◽  
Henrik Hansen ◽  
Pamela Lazo ◽  
Claudia Gutiérrez
Keyword(s):  
Sequential Extraction ◽  
Mine Tailings ◽  
Extraction Method ◽  
Constant Electric Field ◽  
Extraction Procedure ◽  
Water Soluble ◽  
Copper Compounds ◽  
Leaching Solution ◽  
Sequential Extraction Method ◽  
Pre Treatment

Mine tailings have been analyzed by a sequential extraction procedure after their pre-treatment with a leaching solution for 24 h and electrodialytic remediation during 15 days with a constant electric field of 2.7 V cm−1. Four leaching solutions were tested: H2SO4 + HNO3 (2:1 vol.) pH = 1.9; H2SO4 + HNO3 (2:1 vol) pH = 4.2; NH4Cl 0.8M, pH = 5.5 and 30% H2O2 adjusted to pH 2 with HNO3 1M + HCl 1M. After the treatment, the tailings were divided in six slices from anode to cathode. The highest removal efficiency of copper was obtained with H2SO4 + HNO3 pH = 1.9, which allows one to remove 67% of the copper in the total cell and 85% of the copper in the slice closest to anode. The same solution with pH = 4.2 allows one to remove 62% of the total copper. The analysis realized by the sequential extraction method indicates the easy removal of water-soluble and exchangeable fractions in all experiments, moreover, residual and sulfide are the less mobile fractions. The general trend was the movement of copper associated to different fractions from anode to cathode and its accumulation closest to the cathode in the case of exchangeable, Fe-Mn oxides and acid soluble fractions, possibly due to some precipitation of copper compounds associated with less acidic conditions.

Improvement of rheological properties of firm acid gels by skim milk heating is conserved after stirring

2003 ◽  
Vol 70 (4) ◽  
pp. 423-431 ◽  
Author(s):  
P Cayot ◽  
J-F Fairise ◽  
B Colas ◽  
D Lorient ◽  
G Brulé
Keyword(s):  
Storage Modulus ◽  
Skim Milk ◽  
Rheological Parameters ◽  
Water Retention Capacity ◽  
Gel Structure ◽  
Casein Micelles ◽  
Retention Capacity ◽  
Β Lactoglobulin

The enhancement of the strength of set acid gels by heating milk was related to rheological parameters (water retention capacity, storage modulus) of corresponding stirred gels. To obtain accurate rheological data from stirred gel it was necessary to maintain a constant granulometry of gel particles and to recognize time after stirring as a contributing factor. Two hours after stirring, the gel exhibited a higher storage modulus when milk was heated above 80 °C. A measurement of viscosity of just-stirred yoghurt was sufficient to predict correctly the quality of a stirred gel analysed by viscoelastic measurements. Increased resstance to syneresis of just-stirred gels was related to higher viscosity. The quantity of β-lactoglobulin (β-lg) bound to casein micelles explains the improvement of these gel qualities. We have considered that the structure of the initial firm gel (mesostructure level) was conserved in fragments within the stirred gel. Consequently, the explanation given by various authors for the effect of heating milk on the properties of set gels can also be applied to stirred gels. The same mechanism, described in literature for structure formation of set gels from acidified milk is purposed to explain the role of heating milk on the recovery of gel structure after stirring. The β-lg association with casein micelles during heating favoured micelle connections during the acidification. It also favoured the association of gel fragments after stirring during the recovery in gel structure.

scholarly journals Pyrite oxidization accelerates bacterial carbon sequestration in copper mine tailings Type of contribution

2018 ◽  
Author(s):  
Yang Li ◽  
Zhaojun Wu ◽  
Xingchen Dong ◽  
Zifu Xu ◽  
Zhongjun Jia ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Mine Tailings ◽  
Copy Number ◽  
Isotope Labeling ◽  
Gene Copy Number ◽  
Stable Isotope Probing ◽  
Gene Copy ◽  
Cbbl Gene ◽  
Heavy Fractions

Abstract. Polymetallic mine tailings have great potential as carbon sequestration tools to stabilize atmospheric CO2 concentrations. However, previous studies focused on carbonate mineral precipitation, while the role of autotrophs in carbon sequestration by mine tailings has been neglected. In this study, carbon sequestration in two mine tailings treated with FeS2 and 13C-labeled CO2 was analyzed using 13C isotope labeling, pyrosequencing and DNA-based stable isotope probing (SIP) to identify carbon fixers. Mine tailings treated with FeS2 exhibited a higher percentage of 13C atoms (1.76 ± 0.06 in Yangshanchong and 1.36 ± 0.01 in Shuimuchong) than the control groups over a 14-day incubation, as well an increase in the total organic carbon (TOC) content (0.20 ± 0.11 mg/g in Yangshanchong and 0.28 ± 0.14 mg/g in Shuimuchong). These data demonstrated the role of autotrophs in carbon sequestration with pyrite addition. Pyrite treatment led to changes in the composition of bacterial communities, and the genera Sulfobacillus (8.04 %) and Novosphingobium (8.60 %) were found to be dominant in these communities. In addition, the DNA-SIP results indicated that the cbbL gene copy number was 8.20–16.50 times greater than the cbbL gene copy number in 13C-labeled heavy fractions. Furthermore, a Sulfobacillus-like cbbL gene sequence (cbbL-OTU1) accounted for 30.11–34.74 % of all cbbL gene sequences in the 13C-labeled heavy fractions of mine tailings treated with FeS2. These findings highlight the importance of the RubisCO form I-encoding gene, cbbL, in bacterial carbon sequestration and demonstrate the ability of chemoautotrophs to sequester carbon during sulfide mineral oxidation in mine tailings. This study is the first to investigate carbon sequestration by autotrophic groups in mine tailings through the use of isotope tracers and DNA-SIP.

scholarly journals Inhibition of the Anti-Apoptotic Bcl-2 Family by BH3 Mimetics Sensitize the Mitochondrial Permeability Transition Pore Through Bax and Bak

2021 ◽  
Vol 9 ◽  
Author(s):  
Pooja Patel ◽  
Arielys Mendoza ◽  
Dexter J. Robichaux ◽  
Meng C. Wang ◽  
Xander H. T. Wehrens ◽  
...  
Keyword(s):  
Cell Death ◽  
Mitochondrial Dysfunction ◽  
Family Member ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Necrotic Cell Death ◽  
Necrotic Cell ◽  
Inner Mitochondrial Membrane ◽  
Retention Capacity

Mitochondrial permeability transition pore (MPTP)-dependent necrosis contributes to numerous pathologies in the heart, brain, and skeletal muscle. The MPTP is a non-selective pore in the inner mitochondrial membrane that is triggered by high levels of matrix Ca2+, and sustained opening leads to mitochondrial dysfunction. Although the MPTP is defined by an increase in inner mitochondrial membrane permeability, the expression of pro-apoptotic Bcl-2 family members, Bax and Bak localization to the outer mitochondrial membrane is required for MPTP-dependent mitochondrial dysfunction and subsequent necrotic cell death. Contrary to the role of Bax and Bak in apoptosis, which is dependent on their oligomerization, MPTP-dependent necrosis does not require oligomerization as monomeric/inactive forms of Bax and Bak can facilitate mitochondrial dysfunction. However, the relationship between Bax and Bak activation/oligomerization and MPTP sensitization remains to be explored. Here, we use a combination of in vitro and ex vivo approaches to determine the role of the anti-apoptotic Bcl-2 family members, which regulate Bax/Bak activity, in necrotic cell death and MPTP sensitivity. To study the role of each predominantly expressed anti-apoptotic Bcl-2 family member (i.e., Mcl-1, Bcl-2, and Bcl-xL) in MPTP regulation, we utilize various BH3 mimetics that specifically bind to and inhibit each. We determined that the inhibition of each anti-apoptotic Bcl-2 family member lowers mitochondrial calcium retention capacity and sensitizes MPTP opening. Furthermore, the inhibition of each Bcl-2 family member exacerbates both apoptotic and necrotic cell death in vitro in a Bax/Bak-dependent manner. Our findings suggests that mitochondrial Ca2+ retention capacity and MPTP sensitivity is influenced by Bax/Bak activation/oligomerization on the outer mitochondrial membrane, providing further evidence of the crosstalk between the apoptotic and necrotic cell death pathways.

scholarly journals Storm runoff in the foothill headwater area Senotín

2008 ◽  
Vol 3 (No. 3) ◽  
pp. 168-174 ◽  
Author(s):  
M. Tesař ◽  
O. Syrovátka ◽  
M. Šír ◽  
Ľ. Lichner ◽  
J. Váchal ◽  
...  
Keyword(s):  
Czech Republic ◽  
Water Retention ◽  
Pilot Project ◽  
Tile Drainage ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
The Czech Republic ◽  
Subsurface Runoff ◽  
Maximum Retention

The purpose of the pilot project Senot&iacute;n (1993&ndash;2000) was to prove the methods of revitalization of sub-mountain headwater area (0.38 km<sup>2</sup>) in the Novobystřick&aacute; Vysočina Highland (610&ndash;725 m a. s. l.) in the Czech Republic. This area was tile-drained and ploughed in 1985. Seven underground clay shields newly constructed in 1995 stopped the function of the tile drainage. Four balks prevented the surface and subsurface runoff. These adaptations improved water retention capacity of the whole catchment, which is demonstrated using an example of runoff formation in the revitalized area. A typical storm rain (total 15 mm, duration 5.6 h, max. intensity 4 mm/20 min) and the consequent runoff was analysed, including the role of the soil in the runoff retardation and water retention. The runoff started in two hours since the rain beginning. The retention reached 98% of the rain total. The runoff lasted for 85 h. The concave-upward shape of the falling hydrograph limb indicates that the maximum retention capacity of the studied catchment is high.

Use of BCR sequential extraction procedures for soils and plant metal transfer predictions in contaminated mine tailings in Sardinia

2017 ◽  
Vol 172 ◽  
pp. 133-141 ◽  
Author(s):  
Emilia Fernández-Ondoño ◽  
Gianluigi Bacchetta ◽  
Antonio M. Lallena ◽  
Francisco B. Navarro ◽  
Irene Ortiz ◽  
...  
Keyword(s):  
Sequential Extraction ◽  
Mine Tailings ◽  
Metal Transfer ◽  
Bcr Sequential Extraction ◽  
Extraction Procedures ◽  
Sequential Extraction Procedures
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