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首页> 外文期刊>The Science of the Total Environment >Rhizosphere-enhanced biosurfactant action on slowly desorbing PAHs in contaminated soil
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Rhizosphere-enhanced biosurfactant action on slowly desorbing PAHs in contaminated soil

机译：根际生物表面活性剂对受污染土壤中PAHs缓慢解吸的作用

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We studied how sunflower plants affect rhamnolipid biosurfactant mobilization of slowly desorbing fractions of polycyclic aromatic hydrocarbons (PAHs) in soil from a creosote-contaminated site. Desorption kinetics of 13 individual PAHs revealed that the soil contained initially up to 50% slowly desorbing fractions. A rhamnolipid biosurfactant was applied to the soil at the completion of the sunflower cycle (75 days in greenhouse conditions). After this period, the PAHs that remained in the soil were mainly present in a slowly desorbing form as a result of the efficient biodegradation of fast-desorbing PAHs by native microbial populations. The rhamnolipid enhanced the bioavailable fraction of the remaining PAHs by up to 30%, as evidenced by a standardized desorption extraction with Tenax, but the enhancement occurred with only planted soils. The enhanced bioavailability did not decrease residual PAH concentrations under greenhouse conditions, possibly due to ecophysiological limitations in the biodegradation process that were independent of the bioavailability. However, biodegradation was enhanced during slurry treatment of greenhouse planted soils that received the biosurfactant. The addition of rhamnolipids caused a dramatic shift in the soil bacterial community structure, which was magnified in the presence of sunflower plants. The stimulated groups were identified as fast-growing and catabolically versatile bacteria. This new rhizosphere microbial biomass possibly interacted with the biosurfactant to facilitate intra-aggregate diffusion of PAHs, thus enhancing the kinetics of slow desorption. Our results show that the usually limited biosurfactant efficiency with contaminated field soils can be significantly enhanced by integrating the sunflower ontogenetic cycle into the bioremediation design.
机译：我们研究了葵花植物如何影响鼠李糖脂生物表面活性剂的动员，该鼠李素生物表面活性剂可从受杂酚油污染的土壤中缓慢解吸多环芳烃（PAHs）部分。 13种多环芳烃的解吸动力学表明，土壤最初包含高达50％的缓慢解吸组分。在向日葵循环完成时（在温室条件下75天），将鼠李糖脂生物表面活性剂施用于土壤。在此期间之后，由于天然微生物种群对快速吸收的PAHs进行了有效的生物降解，残留在土壤中的PAHs主要以缓慢释放的形式存在。鼠李糖脂可将剩余多环芳烃的生物利用度提高多达30％，这通过使用Tenax进行标准脱附萃取得以证明，但这种提高仅在种植的土壤上发生。在温室条件下，提高的生物利用度不会降低残留的PAH浓度，这可能是由于生物降解过程中与生物利用度无关的生态生理限制所致。但是，在接受生物表面活性剂的温室种植土壤的泥浆处理过程中，生物降解作用得到了增强。鼠李糖脂的添加引起土壤细菌群落结构的急剧变化，这在向日葵植物的存在下被放大。被刺激的组被鉴定为快速生长和分解代谢用途广泛的细菌。这种新的根际微生物生物量可能与生物表面活性剂相互作用，以促进PAHs在聚集体内的扩散，从而增强了缓慢解吸的动力学。我们的研究结果表明，通过将向日葵的发生世代循环整合到生物修复设计中，可以大大提高通常受污染的田间土壤有限的生物表面活性剂效率。

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