Colloids and suspended particulate matters influence on Ni availability in surface waters of impacted ultramafic systems in Brazil

Abstract

International audienceThe overall objective of this work was to assess the modification of Ni availability and lability consequently to anthropic activity. Surface waters were collected in two ultramafic complexes (Barro Alto and Niquelandia) from Goias State (Brazil) impacted by mining and metallurgical activities. For the nearly first time, Isotopic Exchange Kinetic technique (IEK) was performed on these natural water samples to quantify the pool of isotopically exchangeable Ni from the suspended particulate matter (SPM) in water, defined here as E-Ni(W). The SPM mineralogy was investigated by X-Ray Diffraction (XRD), Scanning and Transmission Electron Microscopy (SEM and TEM). This allowed to establish the link between Ni availability and its solid speciation. Goethite, chlorite, talc and serpentine were identified as the main Ni bearing phases in SPM far from metallurgy (Barro Alto site) while in samples located in the area influenced by metallurgy (Niquelandia) Ni was mainly associated to spherical micrometric particles, related to fly ash produced by the ore combustion. In Niquelandia samples 4,1, value was found ranging between 2.4 and 565 mu g L-1, while in Barro Alto E-Ni(W) was 62 mu g L-1, which corresponds to E-Ni values of 49,000 and 2350 mg kg(-1), in SPM from Niquelandia and Barro Alto, respectively. Moreover, IEK experiments highlighted differences in kinetic of Ni exchanges: the maximum E-Ni(W) value was reached after only 19 hours of interaction in Barro Alto sample, while in Niquelandia ones E-Ni(W) hardly reached 70 to 95% of the maximum after the same period of time. On the one hand, both the low proportion and high velocity of Ni exchanges observed in Barro Alto sample may be attributed to surface complexation on talc, serpentine, chlorite and goethite. On the other hand, both the higher proportion of exchangeable stock and slower isotopic exchanges should be mostly attributed in Niquelandia samples to Ni interaction with the anthropogenic spherical and porous particles of Fe-Mg-Si-Al composition, related to FBA released by metallurgic activity

Field availability and mobility of metals in Ferralsols developed on ultramafic rock of Niquelândia, Brazil

“…Since colloidal particles have been proven to play a key role in metal mobility in solutions of soils developed on ultramafic rock (Gasser et al 1994, Zelano et al 2013, Bolaños-Benítez et al 2018), a special investigation was conducted using all solutions sampled during the sampling of February 2008, including runoff waters. A size fractionation approach was performed on soil and surface solutions using the frontal cascade filtration technique (Patel-Sorrentino et al 2007, Garnier et al 2011.…”

Exploring Cd, Cu, Pb, and Zn dynamic speciation in mining and smelting-contaminated soils with stable isotopic exchange kinetics

“…1, Figure S3). It may be partly attributed to the presence of non-labile colloidal fraction of Pb in alkaline soil suspension that leads to the overestimation of E values (Lombi et al, 2003;Ma et al, 2006;Marzouk et al, 2013b;Zelano et al, 2013).…”

An Isotopic Exchange Kinetic Model to Assess the Speciation of Metal Available Pool in Soil: The Case of Nickel

“…The 61 Ni/ 58 Ni isotopic ratio was measured in each filtrate, as well as in spike and standard solutions (SCP Science Plasma CAL) with a High-Resolution ICP-MS (ThermoScientific Element II, IPGP, France). The analytical method used was previously reported in Zelano et al 2013 . The 58 Ni, 60 Ni, 61 Ni, 62 Ni isotopes as well as 56 Fe and 57 Fe were measured to correct possible isobaric interferences on 58 Ni.…”

“…The analytical method used was previously reported in Zelano et al 2013. 35 The 58 Ni, 60 Ni, 61 Ni, 62 Ni isotopes as well as 56 Fe and 57 Fe were measured to correct possible isobaric interferences on 58 Ni. Each isotopic ratio corresponds to an average of 20 runs of 5 scans, allowing an internal analytical reproducibility greater than 0.3% (2SD, n = 210).…”