scholarly journals Mineralogical and geochemical variation in stream sediments impacted by acid mine drainage is related to hydro-geomorphic setting

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
David M. Singer ◽  
Anne J. Jefferson ◽  
Eric L. Traub ◽  
Nicolas Perdrial
Keyword(s):  
Acid Mine Drainage ◽  
Water Chemistry ◽  
Pore Water ◽  
Mine Drainage ◽  
Solid Phase ◽  
Acid Mine ◽  
Dynamic Relationship ◽  
Pore Water Chemistry ◽  
Hydraulic Gradients ◽  
Debris Dam

Acid mine drainage (AMD) discharge has severe, long lasting impacts on water quality and stream ecology in affected watersheds due in part to the dynamic relationship between toxic metals (e.g. Al, Mn, and Cu) and Fe(III) oxy-hydroxides. Localized areas of biogeochemical activity that can mediate mineralogical transformation changes and cause metal release are potentially linked to stream geomorphology. This relationship has not been previously considered with respect to potential longitudinal variation within an impacted stream. The current work aims to determine how Fe(III) (oxy)-hydroxide speciation and distribution, and pore water chemistry in an AMD-impacted streambed, are affected by the presence of two geomorphic structures (a debris dam and step-pool sequence) in an Ohio watershed impacted by historical coal mining. In terms of solid phase mineralogy and geochemistry, in both the tributary and main stem, goethite was the dominant Fe-bearing phase throughout the AMD deposit depth in cores taken upstream of the geomorphic structures, whereas poorly-crystalline phases dominated downstream of the structures, despite the presence of Fe in the reducible fraction. The concentrations and distribution of extractable Al, Mn, and Cu were also different upstream versus downstream of each structure. Pore water Fe and Mn concentrations were higher downstream of the structures than upstream. Strong downward hydraulic gradients were present above the debris dam and in step-pool 1, whereas weaker upward hydraulic gradients were present below the debris dam and in step-pool 2. This work highlights that AMD deposit speciation and distribution, and pore water chemistry, are not spatially uniform within stream reaches, potentially as a result of groundwater-stream exchange-facilitated interactions in the presence of AMD-derived materials.

Contaminants Recovery from Acid Mine Drainage

2016 ◽  
Vol 869 ◽  
pp. 1023-1027 ◽  
Author(s):  
Paulo Lima ◽  
Henrique Takuji Fukuma ◽  
Sandra Nakamatsu ◽  
Maria Gabriela Nogueira Campos ◽  
Maria Gabriela Nogueira Campos ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Rare Earths ◽  
Calcium Sulfate ◽  
Mine Drainage ◽  
Solid Phase ◽  
Hydrated Lime ◽  
Metal Hydroxides ◽  
Triuranium Octoxide ◽  
Acid Mine ◽  
Percentage Yield

In some mines where sulfide minerals can occur in form of pyrite acid mine drainage (AMD) may occur, and it constitutes one of the main environmental impact. In order to prevent that AMD compromises aquifers layers and reaches mine surroundings, a treatment that consists in its neutralization with the use of a hydrated lime suspension is usually conducted. Contaminants that are soluble in AMD are precipitated, remaining in the solid phase. The work here presented aims recover uranium and rare earths found in one of these precipitates, which consists of calcium diuranate and metal hydroxides in a calcium sulfate matrix. This material contains approximately 0.25% of triuranium octoxide (U3O8) and 2.5% of rare earth oxides (TR2O3). The recovery of uranium and rare earths contained in the precipitate was performed through a hydrometallurgical process. The test resulted in a leaching with sulfuric acid presented solubilization of 96% for uranium and 90% for rare earths. A percentage yield of 99.7% and 99.9% was obtained in the steps of uranium extraction and re-extraction from the leachate, respectively.

scholarly journals Diversity of Dissimilatory Sulfite Reductase Genes (dsrAB) in a Salt Marsh Impacted by Long-Term Acid Mine Drainage

2010 ◽  
Vol 76 (14) ◽  
pp. 4819-4828 ◽  
Author(s):  
John W. Moreau ◽  
Robert A. Zierenberg ◽  
Jillian F. Banfield
Keyword(s):  
Salt Marsh ◽  
Acid Mine Drainage ◽  
Pore Water ◽  
Mine Drainage ◽  
Sequence Data ◽  
Rrna Gene ◽  
Ambient Conditions ◽  
Acid Mine ◽  
Dsrab Gene ◽  
Marsh Sediments

ABSTRACT Sulfate-reducing bacteria (SRB) play a major role in the coupled biogeochemical cycling of sulfur and chalcophilic metal(loid)s. By implication, they can exert a strong influence on the speciation and mobility of multiple metal(loid) contaminants. In this study, we combined DsrAB gene sequencing and sulfur isotopic profiling to identify the phylogeny and distribution of SRB and to assess their metabolic activity in salt marsh sediments exposed to acid mine drainage (AMD) for over 100 years. Recovered dsrAB sequences from three sites sampled along an AMD flow path indicated the dominance of a single Desulfovibrio species. Other major sequence clades were related most closely to Desulfosarcina, Desulfococcus, Desulfobulbus, and Desulfosporosinus species. The presence of metal sulfides with low δ34S values relative to δ34S values of pore water sulfate showed that sediment SRB populations were actively reducing sulfate under ambient conditions (pH of ∼2), although possibly within less acidic microenvironments. Interestingly, δ34S values for pore water sulfate were lower than those for sulfate delivered during tidal inundation of marsh sediments. 16S rRNA gene sequence data from sediments and sulfur isotope data confirmed that sulfur-oxidizing bacteria drove the reoxidation of biogenic sulfide coupled to oxygen or nitrate reduction over a timescale of hours. Collectively, these findings imply a highly dynamic microbially mediated cycling of sulfate and sulfide, and thus the speciation and mobility of chalcophilic contaminant metal(loid)s, in AMD-impacted marsh sediments.

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