Instituto de Recursos Naturales y Agrobiología de Sevilla, Consejo Superior de Investigaciones Científicas (IRNAS), CSIC, Sevilla, Spain.
Departamento de Cristalografía, Mineralogía y Química Agrícola, Universidad de Sevilla, Sevilla, Spain.
Sci Total Environ. 2022 Sep 1;837:155744. doi: 10.1016/j.scitotenv.2022.155744. Epub 2022 May 5.
A remediation strategy using three non-toxic availability enhancers (two cyclodextrins and a rhamnolipid biosurfactant) was applied to various soils artificially contaminated with a mix of Polycyclic Aromatic Hydrocarbons (PAHs) considered priority pollutants at two levels of contamination: only with 7 low molecular weight PAHs (LMW PAHs, 5 with 3-ring and 2 with 4-ring - fluoranthene and pyrene) or with 14 PAHs (from 3 to 6 rings). Natural attenuation of PAHs in all soils showed degradation capacity for the LMW PAHs, with a final content of LMW PAHs <5% of their initial concentration. Conversely, the rest of PAHs (high molecular weight PAHs, HMW) remained in the soils (61% - 83.5%), indicating abiotic dissipation of HMW PAHs due to formation of non-extractable residues in soils. The influence of the presence of HMW PAHs on the degradation of the 7 LMW PAHs was also tested, showing a general decrease in the time to obtain 50% dissipation (DT), statistically significant for acenaphthene, acenaphthylene and fluorene. Availability enhancers showed different effects on PAHs dissipation. 2-hydroxypropyl-β-cyclodextrin (HP) decreased DT of some of the lighter PAHs, whereas the rhamnolipid (RL) caused a slight DT increase due to its initial toxicity on native soil microorganisms, but showing later high degradation rate for LMW PAHs. On the contrary, randomly methylated-β-cyclodextrin (RAMEB) slowed down PAHs degradation due to its high adsorption onto soil surface, blocking the desorption of PAHs from the soils. The high number of experimental factors not studied simultaneously before (soil type, co-contamination, availability enhancers and incubation time) allowed to conduct a statistical analysis which supported the conclusions reached. Principal Component Analysis separated the studied PAHs in 3 groups, in relation with their molecular weight and Kow. The first principal component was related with LMW PAHs, and separate the inefficient RAMEB from the other availability enhancers.
采用三种无毒可用性增强剂（两种环糊精和一种鼠李糖脂生物表面活性剂）的修复策略，应用于各种人工污染多环芳烃（PAHs）的土壤，这些 PAHs 被视为两种污染水平的优先污染物：仅含有 7 种低分子量 PAHs（LMW PAHs，其中 5 种具有 3 个环，2 种具有 4 个环——荧蒽和芘）或含有 14 种 PAHs（3 至 6 个环）。所有土壤中 PAHs 的自然衰减均显示出对 LMW PAHs 的降解能力，最终 LMW PAHs 的含量低于初始浓度的 5%。相反，其余的 PAHs（高分子量 PAHs，HMW）仍留在土壤中（61%至 83.5%），表明由于土壤中形成不可提取的残留物，HMW PAHs 发生非生物消解。还测试了 HMW PAHs 的存在对 7 种 LMW PAHs 降解的影响，结果表明，在获得 50%消解（DT）的时间上普遍减少，对于苊、苊烯和芴，这种减少具有统计学意义。可用性增强剂对 PAHs 消解的影响也不同。2-羟丙基-β-环糊精（HP）降低了一些较轻 PAHs 的 DT，而鼠李糖脂（RL）由于其对原生土壤微生物的初始毒性，导致 DT 略有增加，但后来对 LMW PAHs 表现出较高的降解速率。相反，由于其对土壤表面的高吸附性，随机甲基-β-环糊精（RAMEB）会减缓 PAHs 的降解，从而阻止 PAHs 从土壤中解吸。在之前没有同时研究的大量实验因素（土壤类型、共污染、可用性增强剂和培养时间）允许进行统计分析，这支持了得出的结论。主成分分析将研究的 PAHs 分为 3 组，与它们的分子量和 Kow 有关。第一主成分与 LMW PAHs 有关，将低效的 RAMEB 与其他可用性增强剂分开。
