College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
J Hazard Mater. 2009 Dec 30;172(2-3):897-903. doi: 10.1016/j.jhazmat.2009.07.084. Epub 2009 Jul 28.
Understanding the forms and availabilities of polycylic aromatic hydrocarbons (PAHs) would have considerable benefits for their risk assessment, and is of crucial importance for food security and remediation strategies in contaminated sites. In this work, the forms of six PAHs (fluorene, phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, and benzo[a]pyrene) in soils were separated into three fractions including a desorbing fraction, a non-desorbing fraction, and a bound residual fraction using a sequential extraction mass balance approach. The desorbing and non-desorbing fractions were extracted with hydroxypropyl-beta-cyclodextrin (HPCD) and dichloromethane:acetone (1:1, vol/vol), respectively. The desorbing and non-desorbing fractions always dominated the total PAH content in soils. The proportion of bound PAH residue in nonsterilized soils was small (<16%), and even smaller (4.5%) in sterilized soils. The concentrations of the desorbing fraction of PAHs as well as the percentage of this fraction to the total PAH content in soils clearly decreased in 0-16 weeks, which may be due to microbial biodegradation and its transfer to other fractions in soils. The concentrations of the non-desorbing PAH fractions increased in sterilized soils, while remaining nearly constant or decreasing to some extent in nonsterilized soils after 16 weeks. The proportion of non-desorbing PAH fractions significantly increased in 16 week-incubation, and this proportion was positively correlated with the molecular weights of the PAHs tested, indicating that larger PAHs are more likely to be present in non-desorbing fractions. The bound PAH residue tended to increase at first and decrease thereafter over the 0-16-week period, and microbes played an important role in the formation of bound residue.
了解多环芳烃 (PAHs) 的形态和赋存形式将对其风险评估有很大的益处，对于受污染场地的食品安全和修复策略也至关重要。在这项工作中，采用顺序提取质量平衡法将土壤中六种 PAHs（芴、菲、荧蒽、芘、苯并[a]蒽和苯并[a]芘）的形态分离为三个部分，包括可解吸部分、不可解吸部分和结合残留部分。分别用羟丙基-β-环糊精（HPCD）和二氯甲烷：丙酮（1:1，体积/体积）提取可解吸和不可解吸部分。可解吸和不可解吸部分始终在土壤中占总 PAH 含量的主导地位。未灭菌土壤中结合 PAH 残留的比例较小（<16%），在灭菌土壤中甚至更小（4.5%）。在 0-16 周内，土壤中 PAHs 的可解吸部分的浓度以及该部分占土壤中总 PAH 含量的百分比明显降低，这可能是由于微生物生物降解及其向土壤中其他部分的转移。在灭菌土壤中，不可解吸的 PAH 部分的浓度增加，而在未灭菌土壤中，16 周后，其浓度基本保持不变或在一定程度上降低。不可解吸的 PAH 部分的比例在 16 周的培养中显著增加，并且该比例与所测试的 PAHs 的分子量呈正相关，表明较大的 PAHs 更可能存在于不可解吸部分中。结合态 PAH 残留起初呈增加趋势，然后在 0-16 周内逐渐减少，微生物在结合态残留的形成中起着重要作用。
