The characterization, mobility, and persistence of roaster-derived arsenic in soils at Giant Mine, NWT

Abstract Approximately 20,000 tonnes of arsenic (As)-bearing emissions from roasting gold (Au)-bearing arsenopyrite ore were aerially released from 1949 to 1999 at Giant Mine, near Yellowknife, Canada. Soil samples collected within 4 km of the former roaster from sites undisturbed by mining or other human activity contain up to 7700 mg/kg total As. Total As concentrations are highest within a few cm of the surface, and particularly enriched in soil pockets on rock outcrops. Scanning electron microscopy and synchrotron microanalysis show that roaster-derived arsenic trioxide (As2O3) has persisted in shallow soils in the area. Roaster-generated maghemite and hematite are also present. These anthropogenic forms of As are much more common in near-surface soils than natural As-bearing minerals. Comparison of the proportions of As, Sb, and Au concentrations in outcrop soil samples and historic As2O3-rich dust captured by emission controls suggest most of the roaster-derived As in soils at Giant was likely deposited before 1964. Topographic restriction by rock outcrops and a dry, cold climate likely contribute to the persistence of As2O3 in outcrop soils. Limited post-depositional mobility of roaster-generated As is evident from textural relationships in thin section, the presence of As in weathering products, the variation of As:Sb with depth, and the elevated As concentrations in soil pore waters sampled by suction lysimeters. Synthetic gastric and lung fluids extracted an average of 34% and 18% of the total As in three adjacent soil samples. Given that As2O3 is one of the most toxic and bioaccessible forms of As, the persistence of roaster-generated As in shallow soils may be a human health risk at this site.

[1]  R. Salminen,et al.  Arsenic distribution in the environment: the effects of scale. , 2009 .

[2]  H. Jamieson,et al.  The distinction between ore processing and post-depositional transformation on the speciation of arsenic and antimony in mine waste and sediment , 2011 .

[3]  C. Mulligan,et al.  Enhanced mobilization of arsenic and heavy metals from mine tailings by humic acid. , 2009, Chemosphere.

[4]  Arsenic in Lakes Surrounding Yellowknife: Anthropogenic or Naturally Derived? , 2014 .

[5]  D. Craw,et al.  Mineralogical controls on environmental mobility of arsenic from historic mine processing residues, New Zealand , 2008 .

[6]  M. J. Bromstad.  The characterization, persistence, and bioaccessibility of roaster-derived arsenic in surface soils at Giant Mine, Yellowknife, NT , 2011 .

[7]  R. Donahoe,et al.  The form, distribution and mobility of arsenic in soils contaminated by arsenic trioxide, at sites in southeast USA , 2005 .

[8]  G. Calas,et al.  Arsenic in Soils, Mine Tailings, and Former Industrial Sites , 2006 .

[9]  H. Jamieson.  The Legacy of Arsenic Contamination from Mining and Processing Refractory Gold Ore at Giant Mine, Yellowknife, Northwest Territories, Canada , 2014 .

[10]  A. Saada,et al.  Adsorption of arsenic (V) on kaolinite and on kaolinite-humic acid complexes. Role of humic acid nitrogen groups. , 2003, Chemosphere.

[11]  P. Petit,et al.  EXAFS evidence of sorbed arsenic(V) and pharmacosiderite in a soil overlying the Echassières geochemical anomaly, Allier, France , 2002 .

[12]  G. Hall,et al.  THE SPECIATION OF ARSENIC IN IRON OXIDES IN MINE WASTES FROM THE GIANT GOLD MINE, N.W.T.: APPLICATION OF SYNCHROTRON MICRO-XRD AND MICRO-XANES AT THE GRAIN SCALE , 2005 .

[13]  D. Craw,et al.  Field quantification and characterisation of extreme arsenic concentrations at a historic mine processing site, Waiuta, New Zealand , 2009 .

[14]  P. Jardine,et al.  Adsorption, oxidation, and bioaccessibility of As(III) in soils. , 2005, Environmental science & technology.

[15]  Matthew A. Marcus,et al.  Quantitative Speciation of Heavy Metals in Soils and Sediments by Synchrotron X-ray Techniques , 2002 .

[16]  D. Kerr,et al.  Preliminary surficial geology studies and mineral exploration considerations in the Yellowknife area, Northwest Territories , 2000 .

[17]  M. Woo,et al.  Hydrology of subarctic Canadian shield: bedrock upland , 2002 .

[18]  M. Tighe,et al.  The chemistry and behaviour of antimony in the soil environment with comparisons to arsenic: a critical review. , 2010, Environmental pollution.

[19]  D. Craw,et al.  Environmental arsenopyrite stability and dissolution: theory, experiment, and field observations , 2003 .

[20]  D. Macalady,et al.  Natural organic matter affects arsenic speciation and sorption onto hematite. , 2002, Environmental science & technology.

[21]  Matthew Newville,et al.  Spatial and temporal variability of arsenic solid-state speciation in historically lead arsenate contaminated soils. , 2006, Environmental science & technology.

[22]  R. Boyle.  The geochemistry of gold and its deposits (together with a chapter on geochemical prospecting for the element) , 1979 .

[23]  D. Nordstrom,et al.  Arsenic and antimony geochemistry of mine wastes, associated waters and sediments at the Giant Mine, Yellowknife, Northwest Territories, Canada , 2015 .

[24]  Markus Bauer,et al.  Mobilization of arsenic by dissolved organic matter from iron oxides, soils and sediments. , 2006, The Science of the total environment.

[25]  H. Jamieson,et al.  Interaction of diamond mine waste and surface water in the Canadian Arctic , 2006 .

[26]  G. Hall,et al.  The effect of ore roasting on arsenic oxidation state and solid phase speciation in gold mine tailings , 2015 .

[27]  J. Hazemann,et al.  XAS evidence of As(V) association with iron oxyhydroxides in a contaminated soil at a former arsenical pesticide processing plant. , 2005, Environmental science & technology.

[28]  Experimental simulation of soil contamination by arsenolite , 2009 .

[29]  Michael V. Ruby,et al.  Advances in evaluating the oral bioavailability of inorganics in soil for use in human health risk assessment , 1999 .

[30]  David B. Smith,et al.  Application of in vitro extraction studies to evaluate element bioaccessibility in soils from a transect across the United States and Canada. , 2009 .

[31]  Udo Schwertmann,et al.  Thermodynamics of iron oxides: Part III. Enthalpies of formation and stability of ferrihydrite (~Fe( , 2004 .

[32]  D. Burris,et al.  Geochemical and hydrologic controls on the mobilization of arsenic derived from herbicide application , 2009, Applied Geochemistry.

[33]  M. Sadiq.  Arsenic Chemistry in Soils: An Overview of Thermodynamic Predictions and Field Observations , 1997 .

[34]  D. Nordstrom,et al.  Arsenic Speciation and Sorption in Natural Environments , 2014 .

[35]  Suzette A. Morman,et al.  Mine Wastes and Human Health , 2011 .

[36]  Lori A. Wrye.  Distinguishing between natural and anthropogenic sources of arsenic in soils from the Giant mine, Northwest Territories and the North Brookfield mine, Nova Scotia , 2008 .

[37]  J. Hazemann,et al.  Changes in arsenic speciation through a contaminated soil profile: a XAS based study. , 2008, The Science of the total environment.

[38]  D. Kirk Nordstrom,et al.  Arsenic thermodynamic data and environmental geochemistry , 2003 .

[39]  I. Koch,et al.  Effects of organic matter and ageing on the bioaccessibility of arsenic. , 2011, Environmental pollution.

[40]  R. Hancock,et al.  Arsenic pollution in the Yellowknife Area from gold smelter activities , 1982 .

[41]  Christopher S. Kim,et al.  Arsenic Speciation in Solids Using X-ray Absorption Spectroscopy , 2014 .

[42]  J. Rohovec,et al.  Mineralogical and geochemical controls of arsenic speciation and mobility under different redox conditions in soil, sediment and water at the Mokrsko-West gold deposit, Czech Republic. , 2009, The Science of the total environment.

[43]  Martha Buckwalter-Davis.  Automated Mineral Analysis of Mine Waste , 2013 .

[44]  A. Zotov,et al.  Thermodynamic properties and stoichiometry of As (III) hydroxide complexes at hydrothermal conditions , 1996 .