title: Ferric minerals and organic matter change arsenic speciation in copper mine tailings.
abstract: Arsenic (As) is commonly associated with Cu ore minerals, with the resultant risk that As can be released offsite from mine tailings. We used synchrotron-based fluorescence X-ray absorption near-edge spectroscopy (XANES) imaging to provide in situ, laterally-resolved speciation of As within tailings which differed in magnetite content (5-12%) and organic matter content (0-5%). Although the total As content was lower in tailings with low magnetite (LM), the soluble (pore water) As was actually 7-times higher in LM tailings than in high magnetite (HM) tailings. Additionally, amendment with 5% sugarcane mulch residues (SMR) (for revegetation) further increased soluble As due to the dissolution and oxidation of arsenopyrite or orpiment. Indeed, in HM tailings, arsenopyrite and orpiment initially accounted for 88% of the total As, which decreased to 48% upon the addition of SMR - this being associated with an increase in AsV-ferrihydrite from 12% to 52%. In LM tailings, the pattern of As distribution and speciation was similar, with As as AsV-ferrihydrite increasing from 57% to 75% upon the addition of SMR. These findings indicate that changes in ore processing technology, such as the recovery of magnetite could have significant environmental consequences regarding the As mobilisation and transformation in mine tailings.
authors.affiliation: Nanjing Agricultural University, College of Resources and Environmental Sciences, Nanjing, Jiangsu, 210095, China; The University of Queensland, School of Agriculture and Food Sciences, Brisbane, Queensland, 4072, Australia.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: The University of Queensland, Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, Brisbane, Queensland 4072, Australia.
authors.forename: Yunjia
authors.initials: Y
authors.lastname: Liu
authors.affiliation: The University of Queensland, School of Agriculture and Food Sciences, Brisbane, Queensland, 4072, Australia.
authors.forename: Neal W
authors.initials: NW
authors.lastname: Menzies
authors.affiliation: The University of Queensland, School of Agriculture and Food Sciences, Brisbane, Queensland, 4072, Australia.
authors.forename: J Bernhard
authors.initials: JB
authors.lastname: Wehr
authors.affiliation: Australian Synchrotron, Clayton, Victoria, 3168, Australia.
authors.forename: Martin D
authors.initials: MD
authors.lastname: de Jonge
authors.affiliation: Australian Synchrotron, Clayton, Victoria, 3168, Australia.
authors.forename: Daryl L
authors.initials: DL
authors.lastname: Howard
authors.affiliation: The University of Queensland, School of Agriculture and Food Sciences, Brisbane, Queensland, 4072, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kopittke
authors.affiliation: The University of Queensland, Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, Brisbane, Queensland 4072, Australia. Electronic address: l.huang@uq.edu.au.
authors.forename: Longbin
authors.initials: L
authors.lastname: Huang
mesh_terms: D001151:Arsenic / Q000032:analysis*; D001152:Arsenicals / Q000032:analysis*; D003300:Copper; D005290:Ferric Compounds / Q000737:chemistry*; D052203:Ferrosoferric Oxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D058085:Iron Compounds / Q000032:analysis; D008903:Minerals / Q000032:analysis / Q000737:chemistry*; D008906:Mining; D031786:Saccharum; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D012995:Solubility; D013440:Sulfides / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D001152:Arsenicals; D005290:Ferric Compounds; D058085:Iron Compounds; D008903:Minerals; D012987:Soil; D012989:Soil Pollutants; D013440:Sulfides; D014874:Water Pollutants, Chemical; C064510:arsenopyrite; C045816:arsenic trisulfide; D003300:Copper; C092844:ferric oxyhydroxide; D007501:Iron; D001151:Arsenic; D052203:Ferrosoferric Oxide
keywords: Fluorescence-XANES imaging; Laterally-resolved speciation; Magnetite removal; Ore processing technology; Transformation