Global Centre for Environmental Remediation (GCER) , University of Newcastle , Callaghan , New South Wales 2308 , Australia.
Co-operative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) , University of Newcastle , Callaghan , New South Wales 2308 , Australia.
Environ Sci Technol. 2018 Nov 6;52(21):12295-12305. doi: 10.1021/acs.est.8b03008. Epub 2018 Oct 24.
The environmental and health risks associated with "nonextractable" residues (NERs) of polycyclic aromatic hydrocarbons in soils and their potential for remobilization remain largely unexplored. In this novel study, sequential solvent extractions were employed to interrogate time-dependent remobilization of benzo[a]pyrene (B[a]P) NERs and associated kinetics after re-equilibration (REQ) periods lasting 30 d in four artificially spiked soils aged for up to 200 days. Following sequential extractions of the re-equilibrated soils, remobilization of B[a]P NERs was observed and further confirmed by decreases in the absolute amounts of B[a]P recovered following methanolic saponification after REQ. Remobilization may occur through slow intercompartmental partitioning of more sequestered into less sequestered B[a]P fractions in soils. The amounts of B[a]P remobilized in soils decreased throughout aging following first-order kinetics, and the rates of decrease were slow but 2 to 4 times faster than those of extractable B[a]P before re-equilibration. Sandy-clay-loam soils with large amounts of hard organic carbon exhibited less NER remobilization compared to sandy soils. The amounts of remobilized B[a]P decreased significantly ( p < 0.05) with aging. Specifically, butanol-remobilized B[a]P in soils spiked at 10 mg/kg and 50 mg/kg B[a]P ranged from 0.15 to 0.39 mg/kg and 0.67 to 2.30 mg/kg, respectively, after 200 d of aging.
土壤中多环芳烃“不可提取”残留（NER）与其潜在的再迁移相关的环境和健康风险在很大程度上仍未得到探索。在这项新的研究中，采用顺序溶剂提取法研究了在四个人工添加污染的土壤中，长达 200 天老化后，再平衡（REQ）期为 30 天条件下，时间依赖性的苯并[a]芘（B[a]P）NER 再迁移及其相关动力学。对再平衡土壤进行顺序提取后，观察到 B[a]P NER 的再迁移，并通过 REQ 后甲醇皂化后回收的 B[a]P 绝对量减少进一步证实。再迁移可能是由于更被隔离的 B[a]P 分数缓慢地向较不被隔离的 B[a]P 分数进行隔室间分配。在老化过程中，随着一级动力学的进行，土壤中再迁移的 B[a]P 量逐渐减少，且减少速率较慢，但比再平衡前可提取的 B[a]P 快 2 到 4 倍。与沙土壤相比，含有大量硬有机碳的砂壤土-粘土-壤土土壤表现出较少的 NER 再迁移。再迁移的 B[a]P 量随老化而显著减少（p<0.05）。具体而言，在 10 mg/kg 和 50 mg/kg B[a]P 污染的土壤中，老化 200 天后，丁醇提取的再迁移 B[a]P 量分别为 0.15 至 0.39 mg/kg 和 0.67 至 2.30 mg/kg。
