Decreasing arsenic bioaccessibility/bioavailability in soils with iron amendments.
We investigated the use of various iron amendments (metallic Fe and soluble Fe(II)- and Fe(III)-halide salts) to reduce arsenic (As) bioaccessibility (as a surrogate for oral bioavailability) in contaminated soils. Soluble Fe(II)- and Fe(III)-salts were more effective than metallic Fe in reducing As bioaccessibility. Adding soluble Fe(III)-salts to soil reduces As bioaccessibility in two ways, by increasing the Fe(III) (hydr)oxide content and by lowering the soil pH. A detailed investigation into the effect of soil moisture when adding Fe(III) amendments indicated that the reaction can occur in situ if sufficient (>or=30% moisture) is added. If the amendments are added to the soil without moisture, a reduction in bioaccessibility will occur in the extraction fluid itself (i.e., an experimental artifact not reflecting a true in situ reduction in bioaccessibility). Adding Fe (III)-salts to nine As-contaminated soils at a Fe:As molar ratio of 100:1 reduced the average bioaccessibility in the soils by approximately a factor of two. Greater reductions in As bioaccessibility can be achieved by increasing the Fe:As molar ratio. These results suggest decreasing As bioaccessibility and bioavailability in soil by adding Fe amendments may be an effective strategy to remediate As-contaminated soils.
Subacz
Jonathan L
JL
Department of Civil Engineering, Auburn University, Auburn, Alabama, USA.
Barnett
Mark O
MO
Jardine
Philip M
PM
Stewart
Melanie A
MA
D001151:Arsenic / Q000032:analysis* / Q000493:pharmacokinetics; D001682:Biological Availability; D004784:Environmental Monitoring / Q000379:methods*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006801:Humans; D007501:Iron / Q000737:chemistry*; D008954:Models, Biological; D012987:Soil / Q000032:analysis* / Q000592:standards; D012989:Soil Pollutants / Q000032:analysis* / Q000493:pharmacokinetics; D014481:United States
D012987:Soil; D012989:Soil Pollutants; D007501:Iron; D001151:Arsenic