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A novel bioaccessibility prediction method for PAHs in soil: Composite extraction with hydroxypropyl-β-cyclodextrin and extracellular polymer substances

Zhang, Yanan, Yang, Xinglun, Gu, Chenggang, Wang, Fang, Bian, Yongrong, Song, Yang, Wang, Daizhang, Jiang, Xin
The Science of the total environment 2016 v.569-570 pp. 997-1003
active ingredients, bioavailability, bovine serum albumin, correlation, earthworms, lipopolysaccharides, microorganisms, models, polluted soils, polycyclic aromatic hydrocarbons, polymers, prediction, rhamnolipids, risk, sodium alginate, solvents
Hydroxypropyl-β-cyclodextrin (HPCD) extraction has been widely used to estimate bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in soil, but it often underestimates the actual risk due to lack of information regarding the exogenous active substances, such as extracellular polymer substance (EPS) secreted by microorganisms. In this study, a novel technique, composite extraction of HPCD each with rhamnolipid (RL), bovine serum albumin (BSA) and alginate sodium (AS), models of lipopolysaccharide, proteins and polysaccharides, was developed to assess PAHs bioaccessibility to earthworms. In addition, comparisons were conducted with accelerated solvent extraction (ASE) and individual HPCD extraction. The results demonstrated that all chemical extractions were linearly correlated with earthworm accumulation, and individual HPCD extraction underestimated PAH bioaccessibility by about two times. However, the overall performances of the three composite chemical extractions (HPCD/AS, HPCD/RL, HPCD/BSA) were better than individual HPCD extraction, among which, HPCD/AS was best at estimating the earthworm accumulation (considering both correlation coefficient and fitted linear slope). Therefore, all observations implied that HPCD/AS extraction could be used as a fast and reliable method to predict PAH bioaccessibility to earthworms in contaminated soils.