title: Two-liquid-phase system: A promising technique for predicting bioavailability of polycyclic aromatic hydrocarbons in long-term contaminated soils.
abstract: A two-liquid-phase system (TLPS), which consisted of soil slurry and silicone oil, was employed to extract polycyclic aromatic hydrocarbons (PAHs) in four long-term contaminated soils in order to assess the bioavailability of PAHs. Extraction kinetics of six PAHs viz. phenanthrene, fluoranthene, pyrene, benzo(a)anthracene, benzo(a)pyrene, dibenzo(a,h)anthrancene were selected to investigate as they covered the susceptible and recalcitrant PAHs in soil. A parallel experiments were also carried out on the microbial degradation of these PAHs in soil with and without biostimulation (by adding (NH4)2HPO4). The rapidly desorbed fraction of fluoranthene, as indicated by the two-fraction model, was found the highest, ranging from 21.4% to 37.4%, whereas dibenzo(a,h)anthrancene was the lowest, ranging from 8.9% to 20.5%. The rapid desorption of selected PAHs was found to be finished within 24 h. The rapidly desorbed fraction of PAHs investigated using TLPS, was significantly correlated (R2= 0.95) with that degraded by microorganisms in biostimulation treatment. This suggested that the TLPS-assisted extraction could be a promising technique in determining the bioavailability of aged PAHs in contaminated soils. It also suggested that applying sufficient nutrients in bioremediation of field contaminated soils is crucial. Further work is required to test its application to more hydrophobic organic pollutants in long-term contaminated soils.
authors.affiliation: College of Environmental & Resource Sciences, Shanxi University, Taiyuan, 030006, China. Electronic address: wangcongying@sxu.edu.cn.
authors.forename: Congying
authors.initials: C
authors.lastname: Wang
authors.affiliation: College of Environmental & Resource Sciences, Shanxi University, Taiyuan, 030006, China.
authors.forename: Ziyu
authors.initials: Z
authors.lastname: Wang
authors.affiliation: School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan, 030021, China. Electronic address: lizengbo@sina.com.
authors.forename: Zengbo
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Soil Science & Soil and Water Conservation, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, 46300, Pakistan.
authors.forename: Riaz
authors.initials: R
authors.lastname: Ahmad
mesh_terms: D001673:Biodegradation, Environmental; D001682:Biological Availability; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D059625:Liquid-Liquid Extraction; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants
keywords: Biostimulation; Desorption kinetics model; Desorption rate constant; Microbial degradation; Silicone oil