Sammanfattning

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.

Nyckelord

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

Publicerad i

Applied Geochemistry
2016, Volym: 67, sidor: 144-152
Utgivare: PERGAMON-ELSEVIER SCIENCE LTD

SLU författare

• Tiberg, Charlotta

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    
  • Statens geotekniska institut (SGI)

• Gustafsson, Jon-Petter

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    
  • Kungliga Tekniska Högskolan (KTH)

• Marsz, Aleksandra

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    

• Persson, Ingmar

  • Institutionen för kemi och bioteknologi, Sveriges lantbruksuniversitet
    

• Berggren Kleja, Dan

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    
  • Statens geotekniska institut (SGI)

Globala målen

SDG15 Skydda, återställa och främja ett hållbart nyttjande av landbaserade ekosystem, hållbart bruka skogar, bekämpa ökenspridning, hejda och vrida tillbaka markförstöringen samt hejda förlusten av biologisk mångfald


UKÄ forskningsämne

Miljöledning
Geokemi


Publikationens identifierare

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

Permanent länk till denna sida (URI)

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