Arsenic and antimony geochemistry of historical roaster waste from the Giant Mine, Yellowknife, Canada

Lum, Jullieta; Schoepfer, Valerie A.; Jamieson, Heather E.; McBeth, Joyce; Radková, Anežka Borčinová; Walls, Mary; Lindsay, Matthew B.J.

doi:10.1016/j.jhazmat.2023.132037

Cited by 6 publications

(1 citation statement)

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“…Linear-combination fitting of the XANES spectra (XANES-LCF) was conducted in ATHENA from 20 eV below to 30 eV above the As K-edge . Arsenate and arsenite adsorbed to ferrihydrite were considered as references in XANES-LCF because ferrihydrite is a common sorbent of As in soils and is likely a dominant Fe-(oxyhydr)oxide phase in organic-rich permafrost terranes where active Fe-redox recycling occurs .…”

Section: Methodsmentioning

confidence: 99%

Arsenic Mobilization from Thawing Permafrost

Skierszkan,

Schoepfer,

Fellwock

et al. 2024

ACS Earth Space Chem.

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Thawing permafrost releases labile organic carbon and alters groundwater geochemistry and hydrology with uncertain outcomes for the mobility of hazardous metal(loid)s. Managing water quality in thawing permafrost regions is predicated on a detailed understanding of the speciation and abundance of metal(loid)s in permafrost soils and porewaters produced during thaw, which remains limited at present. This study contributes new knowledge on the sources and fate of arsenic during the thaw of organic-rich permafrost using samples collected from a subarctic permafrost region associated with geogenic arsenic (Dawson Range, Yukon, Canada). Several permafrost cores and active-layer samples from this region were analyzed for their solid-phase and aqueous geochemical characteristics and their arsenic speciation. Porewaters were extracted from permafrost cores after thaw under anaerobic conditions for aqueous geochemical analyses. Bedrock samples from the field site were also analyzed for arsenic speciation and mineralogy. X-ray diffraction and X-ray near-edge spectroscopy (XANES) analyses of weathered bedrock upgradient of soil sampling locations contained arsenic(V) hosted in iron-(oxyhydr)oxides and scorodite. XANES and micro X-ray fluorescence analyses of permafrost soils indicated a mixture of arsenic(III) and arsenic(V), indicating redox recycling of arsenic. Soil-bound arsenic was colocated with iron, likely as arseniferous iron-(oxyhydr)oxides that have been encapsulated by aggrading permafrost over geologic time. However, permafrost thaw produced porewater containing elevated dissolved arsenic (median 40 μg L −1 , range 2−96 μg L −1 ). Thawed permafrost porewater also contained elevated dissolved iron (median 5.5 mg L −1 , range 0.5−40 mg L −1 ) and dissolved organic carbon (median 423 mg L −1 , range 72−3240 mg L −1 ), indicative of reducing conditions. This study highlights that arsenic can be found in reactive forms in permafrost soil, and that its thaw can release arsenic and iron to porewater and produce poor water quality.

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Section: Methodsmentioning

confidence: 99%

Arsenic Mobilization from Thawing Permafrost

Skierszkan,

Schoepfer,

Fellwock

et al. 2024

ACS Earth Space Chem.

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Metal(loid)s Removal Response to the Seasonal Freeze–Thaw Cycle in Semi-passive Pilot Scale Bioreactors

Desmau,

Simister,

Baldwin

et al. 2024

Mine Water Environ

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There is an increasing demand for cost-effective semi-passive water treatment that can withstand challenging climatic conditions and effectively and sustainably manage mine-impacted water in (sub)arctic regions. This study investigated the ability of four pilot-scale bioreactors inoculated with locally sourced bacteria and affected by a freeze–thaw cycle to remove selenium and antimony. The bioreactors were operated at a Canadian (sub)arctic mine for a year. Two duplicate bioreactors were installed in a heated shed that was maintained at 5 °C over the winter, while two other duplicates were installed outdoors and left to freeze. The removal rate of selenium and antimony was monitored weekly, while a genomic characterization of the microbial populations in the bioreactors was performed monthly. The overall percentage of selenium and antimony removal was similar in the outside (10–93% Se, 20–96% Sb) and inside (35–94% Se, 10–95% Sb) bioreactors, apart from the spring thawing period when removal in the outdoor bioreactors was slightly lower for Se. The dominant taxonomic groups of microbial populations in all bioreactors were Bacteroidota, Firmicutes, Desulfobacterota and Proteobacteria. The microbial population composition was consistent and re-established quickly after spring thaw in the outside bioreactors. This demonstrated that the removal capacity of bioreactors inoculated with locally sourced bacteria was mostly unaffected by a freeze–thaw cycle, highlighting the strength of using local resources to design bioreactors in extreme climatic conditions.

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