Study of Ni exchangeable pool speciation in ultramafic and mining environments with isotopic exchange kinetic data and models |
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| Institution: | 1. Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ. Paris Diderot, UMR 7154 CNRS, F-75005 Paris, France;2. Univeristà degli Studi di Torino, Via Pietro Giuria 5, 10125 Torino, Italy;3. UMR8148 GEOPS, Univ. Paris Sud-CNRS-Université Paris Saclay, Rue du Belvédère, Bât. 504, 91405 Orsay Cedex, France;4. Univ. Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086 CNRS, F-75205 Paris, France;5. Universidade de Brasilia, IG/GMP-ICC Centro, 70919-970 Brasilia-DF, Brazil;1. CT-scanner Facility, Central Analytical Facilities, Stellenbosch University, South Africa;2. Department of Earth Sciences, Stellenbosch University, South Africa;3. Department of Soil Science, Stellenbosch University, South Africa;1. Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan;2. Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529, USA;1. Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada;2. National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, AB, T6G 2M9, Canada;1. Centre for Coastal and Catchment Research, River Basin Dynamics and Hydrology Research Group, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, Ceredigion, SY23 3DB, UK;2. School of Environment, Natural Resources and Geography, Bangor University, Bangor, Gwynedd, LL55 1YW, UK;3. Innovative River Solutions, Institute of Agriculture and Environment, Massey University, Private Bag 11 222, Palmerston North, 4442, New Zealand;1. Laboratoire de Spectrochimie IR et Raman, UMR-CNRS 8516, Bât. C5 Université de Lille I, 59655 Villeneuve d''Ascq Cedex, France;2. Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, UMR-CNRS 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France;3. Université de Cergy-Pontoise, Géosciences et Environnement Cergy, EA 4506, 95000 Cergy-Pontoise, France |
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| Abstract: | Soils and ore samples influenced by mining and metallurgical activity were collected in ultramafic soils (UM) complexes of Barro Alto and Niquelândia, in order to determine the contribution of each Ni bearing phases to the total exchangeable pool of Ni, and to point out if this pool was affected by anthropic activities. For this purpose, the IEK-model previously developed by the group (Zelano et al., submitted) was applied, on the basis of IEK experiments performed on pure typical Ni scavengers (serpentines, chlorite, smectite and iron oxydes) from ultramafic systems. For each typical scavenger, this model describes the percentage of Ni associated to exchangeable pool(s) as well as their corresponding kinetic constant(s) of exchange. The mineralogical composition of soil and ore samples and Ni solid speciation were first determined, and the IEK-model was applied on these bases. In almost all samples, an important contribution of serpentine to Ni exchangeable pool was highlighted, ranging between 10% and 45%. The important amount of organic matter (OM) in one of the studied soil samples, allowed to extrapolate generic OM ENi and k parameters, which were introduced in the IEK-model to improve its predictive capability. Obtained results provided evidences of how even a small content (3 wt%) of organic carbon (OC), can represent an important contribution of OM to the total ENi pool (60%). In the investigated ore samples, up to the 60% of ENi was attribute to smectite, responsible for fast ENi pool kinetic evolution. In addition, the model highlighted the role of the Fine Black Ash (FBA), by-products of the pyrometallurgical activity, detected into a soil sample, that is responsible for the 15% of ENi. This approach allowed to determine, for the first time, the relative contribution of each Ni bearing phase to the total exchangeable pool, in terms of concentration and kinetics. |
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| Keywords: | Ultramafic soils Isotopic exchange kinetics Solid speciation Mine waste Nickel-availability Modeling |
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