THE ROLE OF FE OXYHYDROXIDES IN REMEDIATION OF CONTAMINETED MINE WATERS

2019 ◽  
Author(s):  
Ondrej Brachtýr
Keyword(s):  
Mine Waters ◽  
Fe Oxyhydroxides

scholarly journals Mobilisation and Bioavailability of Arsenic Around Mesothermal Gold Deposits in a Semiarid Environment, Otago, New Zealand

2002 ◽  
Vol 2 ◽  
pp. 308-319 ◽  
Author(s):  
D. Craw ◽  
L. Pacheco
Keyword(s):  
New Zealand ◽  
Vadose Zone ◽  
Surface Waters ◽  
Gold Deposits ◽  
Processing Plant ◽  
Geological Time ◽  
Iron Oxyhydroxides ◽  
Mine Waters ◽  
Evaporative Concentration ◽  
Fe Oxyhydroxides

Arsenopyrite (FeAsS) is the principal arsenic (As) mineral in mineralised mesothermal veins (typically 5,000 mg/kg As) in southeastern New Zealand. Groundwater in contact with arsenopyrite-bearing rocks has elevated As concentrations (up to 0.1 mg/l). The arsenopyrite decomposes slowly on oxidation in soils and historic mine workings in a cool semiarid climate. Dissolved As is predominantly As(III) in association with arsenopyrite, but this is rapidly oxidised over days to weeks to As(V) in the vadose zone. Oxidation is facilitated by particulate Fe and/or Mn oxyhydroxides, and by bacteria in surface waters. Evaporative concentration of dissolved As(V) in the vadose zone causes precipitation of scorodite (Fe(III)As(V)O4.2H2O). Adsorption of As(V) to Fe oxyhydroxides in soils and groundwater pathways lowers dissolved As concentrations. Soils over mineralised veins typically have <200 mg/kg As, as most As is removed in solution on geological time scales. Most plants on the mineralised rocks and soils do not take up As, although some inedible species can fix up to 18 mg/kg As. Hence, bioavailability of As(V) is low in this environment, despite the substantial As flux.Similar As mobility is seen in an active gold mine processing plant and tailings. Arsenopyrite dissolves more rapidly on agitation, and mine waters can have dissolved As >200 mg/l, predominantly as As(V). This dissolved As decreases in tailings waters to near 2 mg/l, mainly as As(III) when in contact with arsenopyrite. Weak oxidation of evaporatively dried tailings causes cementation with scorodite and iron oxyhydroxides, and scorodite precipitation exerts some control on dissolved As(V) concentrations. High dissolved As in mine waters is lowered by adsorption to iron oxyhydroxides, and waters discharged from the mine site have negligible dissolved As.

scholarly journals Use of Aquatic Plants in Mine Wastewater Purification

2019 ◽  
pp. 1-7
Author(s):  
Kh. S. Turdaliyeva ◽  
S. A. Huzhzhiev ◽  
K. S. Safarov
Keyword(s):  
Aquatic Plants ◽  
Eichhornia Crassipes ◽  
Chemical Elements ◽  
Mine Waters ◽  
Study Results ◽  
Elemental Analyses ◽  
Before And After ◽  
Mine Wastewater ◽  
Organ Specific

A comparative study of the role of some aquatic plants in the biological treatment of wastewater from the “Koch-Bulak” mine of the Angren mining department were carried out. The experiments were taken in laboratory conditions in aquariums. Hydrochemical and elemental analyses of wastewater from the Koch-Bulak mine of the Angren mining department were carried out  before and after the cultivation of Carolina azolla, Pistis teloreous and Eichhornia crassipes. Features of the growth and development of the studied plants in the mine wastewater are identified. The smallest increase in biomass in the laboratory showed Carolina azolla, the largest - Pistis teloreous. Elemental composition of the studied plants was carried out by the neutron activation analysis. Specific and organ-specific differences in the accumulation of chemical elements in the biomass of aquatic macrophytes are revealed as well. The study results revealed possibilities of use of the aquatic plants: Carolina azolla, Pistis teloreous and Eichhornia crassipes for the purpose of mine waters’ purification with high effectiveness.

scholarly journals Water oxidation kinetics of nanoporous BiVO4 photoanodes functionalised with nickel/iron oxyhydroxide electrocatalysts

2021 ◽  
Author(s):  
Laia Francàs ◽  
Shababa Selim ◽  
Sacha Corby ◽  
Dongho Lee ◽  
Camilo A. Mesa ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Water Oxidation ◽  
Oxidation Kinetics ◽  
Charge Accumulation ◽  
Iron Oxyhydroxide ◽  
Nickel Iron ◽  
Co Catalysts ◽  
Fe Oxyhydroxides ◽  
Kinetics Of

Elucidating the role of charge accumulation and reaction kinetics in governing the performance of Ni/Fe oxyhydroxides as electrocatalysts and as co-catalysts on BiVO4 photoanodes water oxidation.

scholarly journals Microbial chemolithotrophy mediates oxidative weathering of granitic bedrock

2019 ◽  
Vol 116 (52) ◽  
pp. 26394-26401 ◽  
Author(s):  
Stephanie A. Napieralski ◽  
Heather L. Buss ◽  
Susan L. Brantley ◽  
Seungyeol Lee ◽  
Huifang Xu ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Gene Clusters ◽  
Growth Conditions ◽  
Primary Energy ◽  
Quartz Diorite ◽  
Extracellular Electron Transfer ◽  
Mineral Surfaces ◽  
Transmission Electron ◽  
Fe Oxyhydroxides

The flux of solutes from the chemical weathering of the continental crust supplies a steady supply of essential nutrients necessary for the maintenance of Earth’s biosphere. Promotion of weathering by microorganisms is a well-documented phenomenon and is most often attributed to heterotrophic microbial metabolism for the purposes of nutrient acquisition. Here, we demonstrate the role of chemolithotrophic ferrous iron [Fe(II)]-oxidizing bacteria in biogeochemical weathering of subsurface Fe(II)-silicate minerals at the Luquillo Critical Zone Observatory in Puerto Rico. Under chemolithotrophic growth conditions, mineral-derived Fe(II) in the Rio Blanco Quartz Diorite served as the primary energy source for microbial growth. An enrichment in homologs to gene clusters involved in extracellular electron transfer was associated with dramatically accelerated rates of mineral oxidation and adenosine triphosphate generation relative to sterile diorite suspensions. Transmission electron microscopy and energy-dispersive spectroscopy revealed the accumulation of nanoparticulate Fe–oxyhydroxides on mineral surfaces only under biotic conditions. Microbially oxidized quartz diorite showed greater susceptibility to proton-promoted dissolution, which has important implications for weathering reactions in situ. Collectively, our results suggest that chemolithotrophic Fe(II)-oxidizing bacteria are likely contributors in the transformation of rock to regolith.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

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