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Immobilization of Cu and As in two contaminated soils with zero-valent iron - Long-term performance and mechanisms
KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. Swedish University of Agricultural Sciences.ORCID iD: 0000-0001-8771-7941
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2016 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 67, 144-152 p.Article in journal (Refereed) PublishedText
Abstract [en]

Immobilization of trace elements in contaminated soils by zero-valent iron (ZVI) is a promising remediation method, but questions about its long-term performance remain unanswered. To quantify immobilization and predict possible contaminant remobilization on long timescales detailed knowledge about immobilization mechanisms is needed. This study aimed at assessing the long-term effect of ZVI amendments on dissolved copper and arsenic in contaminated soils, at exploring the immobilization mechanism(s), and at setting up a geochemical model able to estimate dissolved copper and arsenic under different scenarios. Samples from untreated and ZVI-treated plots in two field experiments where ZVI had been added 6 and 15 years ago were investigated by a combination of batch experiments, geochemical modeling and extended X-ray absorption fine structure (EXAFS) spectroscopy. Dissolved copper and arsenic concentrations were described by a multisurface geochemical model with surface complexation reactions, verified by EXAFS. The ZVI remained "reactive" after 6-15 years, i. e. the dissolved concentrations of copper and arsenic were lower in the ZVI-treated than in the untreated soils. There was a shift in copper speciation from organic matter complexes in the untreated soil to surface complexes with iron (hydr)oxides in the ZVI-treated soil. The pH value was important for copper immobilization and ZVI did not have a stabilizing effect if pH was lower than about 6. Immobilization of arsenic was slightly pH-dependent and sensitive to the competition with phosphate. If phosphate was ignored in the modeling, the dissolution of arsenate was greatly underestimated. (C) 2016 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 67, 144-152 p.
Keyword [en]
Copper, Arsenic, ZVI, Zero-valent iron, Iron (hydr)oxide, Immobilization, Stabilization, Contaminated soil, Remediation, Geochemical modeling, Surface complexation model, EXAFS spectroscopy, X-ray absorption spectroscopy
National Category
Geochemistry
Identifiers
URN: urn:nbn:se:kth:diva-185608DOI: 10.1016/j.apgeochem.2016.02.009ISI: 000372720900013ScopusID: 2-s2.0-84959353433OAI: oai:DiVA.org:kth-185608DiVA: diva2:924263
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

QC 20160428

Available from: 2016-04-28 Created: 2016-04-25 Last updated: 2016-06-20Bibliographically approved

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The full text will be freely available from 2018-02-21 08:29
Available from 2018-02-21 08:29

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Gustafsson, Jon Petter
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Land and Water Resources Engineering
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