Arsenic and antimony geochemistry of mine wastes, associated waters and sediments at the Giant Mine, Yellowknife, Northwest Territories, Canada

Abstract

Elevated levels of arsenic (As) and antimony (Sb) in water and sediments are legacy residues found downstream from gold-mining activities at the Giant Mine in Yellowknife, Northwest Territories (NWT), Canada. To track the transport and fate of As and Sb, samples of mine-waste from the mill, and surface water, sediment, pore-water, and vegetation downstream of the mine were collected. Mine waste, porewater, and sediment samples were analyzed for bulk chemistry, and aqueous and solid-state speciation. Sediment and vegetation chemistry were evaluated using scanning electron microscope imaging, synchrotron-based element mapping and electron microprobe analysis. The distributions of As and Sb in sediments were similar, yet their distributions in the corresponding pore-waters were mostly dissimilar, and the mobility of As was greater than that of Sb. The aqueous and solid-state speciation of As and Sb also differed. In pore-water, As(V) dominated in oxidizing environments and As(III) in reducing environments. In contrast, the Sb(V) species dominated in all but one pore-water sample, even under reducing conditions. The As(V)-O solid phase became depleted with depth below the sediment-water interface, and the Sb(V)-O phase persisted under relatively reducing conditions. In the surficial zone at a site populated by Equisetum fluviatile (common horsetail), As and Sb were associated with organic material and appeared mobile in the root zone. In the zone below active plant growth, As and Sb were associated primarily with inorganic phases suggesting a release and reprecipitation of these elements upon plant death. The coexistence of reduced and oxidized As and Sb species, instability of some phases under changing redox conditions, and plant uptake and release pose challenges for remediation efforts at the

Speciation dynamics of oxyanion contaminants (As, Sb, Cr) in argillaceous suspensions during oxic-anoxic cycles

“…Fast reductive precipitation of Sb agrees with the absence of aqueous Sb (III) and the co-existence of Sb(V) with As(III) in the experimental solutions of Exp. II and III, as previously demonstrated in other studies (Casiot et al, 2007;Fawcett et al, 2015;Mitsunobu et al, 2006). The model fit to the experimental data requires a two-step process: sorption of Sb(V) followed by its reduction at the mineral surfaces, presumably via a detoxification pathway (Table 2, R 21 ).…”

“…3: h). Recent studies have demonstrated that under anoxic conditions, Sb(V) can act as a TEA for microbial respiration (Abin and Hollibaugh, 2014), but also that Sb(V) respiration is inhibited by the presence of aqueous As(V) (Fawcett et al, 2015;Kulp et al, 2014;Mitsunobu et al, 2006). Thus, Sb(V) respiration could explain the increase of ATP observed in Exp.…”

Performance of polymer-enhanced bentonite–sand mixture for covering arsenic-rich gold mine tailings for up to 4 years

“…Arsenic is a well-known toxic element; therefore, human exposure to gold mine tailings by inhalation or ingestion is a health hazard that can result in a variety of diseases including various forms of cancer, cardiovascular and peripheral diseases (Hopenhyan-Rich et al 1996;Kaltreider et al 2001;Walker et al 2009). In addition, Gold mine tailings represent a source of potential or observed groundwater and surface water contamination in Canada Fawcett et al 2015) and elsewhere in the world (Rösner and Schalkwyk 2000;Kiventerä et al 2016). …”

Bioleaching of Arsenic and Antimony from Mining Waste

“…Microorganisms and their metabolic processes are very important parts of biogeochemical cycles of chemical elements. They significantly affect mobility, toxicity, bioavailability a solubility of potentially toxic metals and metalloids in the environment (FAWCETT et al 2015). Balance between mobility and immobilization of chemical elements, including arsenic and antimony, is affected mainly by microorganisms, their surrounding environment and physic-chemical conditions of this environment.…”