Abstract

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.

Keywords

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

Published in

Applied Geochemistry
2016, Volume: 67, pages: 144-152
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

• Tiberg, Charlotta

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Swedish Geotechnical Institute (SGI)

• Gustafsson, Jon-Petter

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Royal Institute of Technology (KTH)

• Marsz, Aleksandra

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Persson, Ingmar

  • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences
    

• Berggren Kleja, Dan

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Swedish Geotechnical Institute (SGI)

Sustainable Development Goals

Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


UKÄ Subject classification

Environmental Management
Geochemistry


Publication identifier

DOI: https://doi.org/10.1016/j.apgeochem.2016.02.009

Permanent link to this page (URI)

https://res.slu.se/id/publ/76409