Moseley Rebecca A, Barnett Mark O, Stewart Melanie A, Mehlhorn Tonia L, Jardine Philip M, Ginder-Vogel Matthew, Fendorf Scott
Dep. of Civil Engineering, 208 Harbert Engineering Ctr., Auburn Univ., Auburn, AL 36849, USA.
J Environ Qual. 2008 Oct 23;37(6):2116-24. doi: 10.2134/jeq2007.0426. Print 2008 Nov-Dec.
In-situ stabilization using phosphate (P) amendments, such as P-based fertilizers and rock, are a potentially cost-effective and minimally disruptive alternative for stabilizing Pb in soils. We examined the effect of time (0-365 d), in vitro extraction pH (1.5 vs. 2.3), and dosage of three P-based amendments on the bioaccessibility (as a surrogate for oral bioavailability) of Pb in 10 soils from U.S. Department of Defense facilities. Initial untreated soil bioaccessibility consistently exceeded the U.S. Environmental Protection Agency default value of 60% relative bioavailability, with higher bioaccessibility consistently observed at an in vitro extraction pH of 1.5 vs. 2.3. Although P-based amendments statistically (P < 0.05) reduced bioaccessibility in many instances, with reductions dependent on the amendment and dosage, large amendment dosages (approximately 20-25% by mass to yield 5% P by mass) were required to reduce average bioaccessibility by approximately 25%. For most amendment combinations, reductions continued to occur for periods up to 1 yr, indicating that the observed reductions were not merely experimental artifacts of the in vitro extraction procedure. Although our results indicated that reductions in Pb bioaccessibility with P amendments are technically feasible, relatively large amendment masses were required to achieve relatively modest reductions in bioaccessibility. The cost and potential environmental implications of adding such large amounts of P may limit the practicality of in situ immobilization for some Pb-contaminated soils, industrial and firing range soils in particular.
使用基于磷（P）的改良剂（如磷肥和岩石）进行原位稳定化处理，是一种在土壤中稳定铅的潜在经济高效且干扰最小的替代方法。我们研究了时间（0 - 365天）、体外提取pH值（1.5对2.3）以及三种基于磷的改良剂的用量对来自美国国防部设施的10种土壤中铅的生物可及性（作为口服生物利用度的替代指标）的影响。未经处理的初始土壤生物可及性始终超过美国环境保护局默认的60%相对生物利用度值，在体外提取pH值为1.5时始终观察到比pH值为2.3时更高的生物可及性。尽管基于磷的改良剂在许多情况下能使生物可及性在统计学上显著降低（P < 0.05），且降低程度取决于改良剂和用量，但需要大量的改良剂用量（按质量计约20 - 25%以产生5%的磷按质量计）才能使平均生物可及性降低约25%。对于大多数改良剂组合，生物可及性的降低在长达1年的时间内持续存在，这表明观察到的降低不仅仅是体外提取过程的实验假象。尽管我们的结果表明用磷改良剂降低铅的生物可及性在技术上是可行的，但需要相对大量的改良剂才能实现生物可及性相对适度的降低。添加如此大量的磷的成本和潜在环境影响可能会限制对某些受铅污染的土壤（特别是工业土壤和射击场土壤）进行原位固定的实用性。
