Subacz Jonathan L, Barnett Mark O, Jardine Philip M, Stewart Melanie A
Department of Civil Engineering, Auburn University, Auburn, Alabama, USA.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2007 Jul 15;42(9):1317-29. doi: 10.1080/10934520701436047.
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.
我们研究了使用各种铁改良剂（金属铁以及可溶性二价铁和三价铁卤化物盐）来降低污染土壤中砷（As）的生物可及性（作为口服生物利用度的替代指标）。可溶性二价铁盐和三价铁盐在降低砷生物可及性方面比金属铁更有效。向土壤中添加可溶性三价铁盐通过增加三价铁（氢）氧化物含量和降低土壤pH值这两种方式来降低砷的生物可及性。对添加三价铁改良剂时土壤湿度影响的详细研究表明，如果添加足够的水分（≥30%湿度），反应可在原位发生。如果在没有水分的情况下将改良剂添加到土壤中，提取液本身的生物可及性会降低（即一种实验假象，并非反映生物可及性的真实原位降低）。以铁与砷摩尔比为100:1向九种受砷污染的土壤中添加三价铁盐，可使土壤中的平均生物可及性降低约一半。通过增加铁与砷的摩尔比可实现更大程度的砷生物可及性降低。这些结果表明，通过添加铁改良剂来降低土壤中砷的生物可及性和生物利用度可能是修复受砷污染土壤的有效策略。
