title: Degradation mechanisms of benzo[a]pyrene and its accumulated metabolites by biodegradation combined with chemical oxidation.
abstract: A high degradation extent of benzo[a]pyrene (BaP) should not be considered as the sole desirable criterion for the bioremediation of BaP-contaminated soils because some of its accumulated metabolites still have severe health risks to human. Two main metabolites of BaP, benzo[a]pyrene-1,6-quinone (BP1,6-quinone) and 3-hydroxybenzo[a]pyrene (3-OHBP) were identified by high performance liquid chromatography (HPLC) with standards. This study was the first time that degradation of both BaP and the two metabolites was carried out by chemical oxidation and biodegradation. Three main phases during the whole degradation process were proposed. Hydrogen peroxide-zinc (H(2)O(2)-Zn), the fungus - Aspergillus niger and the bacteria - Zoogloea sp. played an important role in the different phases. The degradation parameters of the system were also optimized, and the results showed that the effect of degradation was the best when fungus-bacteria combined with H(2)O(2)-Zn, the concentration range of BaP in the cultures was 30-120mg/l, the initial pH of the cultures was 6.0. However, as co-metabolites, phenanthrene significant inhibited the degradation of BaP. This combined degradation system compared with the conventional method of degradation by domestic fungus only, enhanced the degradation extent of BaP by more than 20% on the 12d. The highest accumulation of BP1,6-quinone and 3-OHBP were reduced by nearly 10% in the degradation experiments, which further proved that the combined degradation system was more effective as far as joint toxicity of BaP and its metabolites are concerned.
authors.affiliation: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
authors.forename: Shuyan
authors.initials: S
authors.lastname: Zang
authors.forename: Peijun
authors.initials: P
authors.lastname: Li
authors.forename: Wenxiu
authors.initials: W
authors.lastname: Li
authors.forename: Dong
authors.initials: D
authors.lastname: Zhang
authors.forename: Andrew
authors.initials: A
authors.lastname: Hamilton
mesh_terms: D001230:Aspergillus / Q000378:metabolism; D001564:Benzo(a)pyrene / Q000737:chemistry* / Q000378:metabolism; D001673:Biodegradation, Environmental; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000737:chemistry; D010084:Oxidation-Reduction; D010616:Phenanthrenes / Q000032:analysis; D020156:Salicylic Acid / Q000032:analysis; D012988:Soil Microbiology; D015045:Zoogloea / Q000378:metabolism
chemical_list: D008670:Metals; D010616:Phenanthrenes; D001564:Benzo(a)pyrene; C031181:phenanthrene; D006861:Hydrogen Peroxide; D020156:Salicylic Acid