title: Phenanthrene sorption to soil humic acid and different humin fractions.
abstract: This study was undertaken to provide an insight into the effect of heterogeneous soil organic matter (SOM) on the sorption of phenanthrene. Humic acid (HA) and humin were extracted from a peat soil. Humin was further fractionated into bound-humic acid (BHA), lipid, and insoluble residue (IR) fractions. Heterogeneous natures of these fractions were characterized by elemental analysis, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and solid-state 13C NMR. Aliphaticity of the fractions followed the order lipid >BHA > HA > IR, while the polarity order was IR > BHA> HA > lipid. Sorption of phenanthrene on these fractions fitted the Freundlich equation, suggesting that phenanthrene sorption isotherms of lipid were almost linear (N = 0.993), while those of HA, BHA, and IR were nonlinear, with N values ranging from 0.723 to 0.910. The N values followed the order lipid > HA > BHA > IR and were significantly correlated inversely with their polarities (p < 0.05). Organic carbon-normalized sorption coefficients (K(FOC)) were independent of aliphatic or aromatic contents of the SOM fractions. The results suggested that SOM, especially for the humin fractions, was highly heterogeneous in terms of elemental composition, structure, and polarity. Such heterogeneity was considered to be responsible forthe nonlinear sorption of phenanthrene.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, P. O. Box 2871, Beijing 100085, China. bwen@rcees.ac.cn
authors.forename: Bei
authors.initials: B
authors.lastname: Wen
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Zhang
authors.forename: Shu-Zhen
authors.initials: SZ
authors.lastname: Zhang
authors.forename: Xiao-Quan
authors.initials: XQ
authors.lastname: Shan
authors.forename: Shahamat U
authors.initials: SU
authors.lastname: Khan
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D000327:Adsorption; D006812:Humic Substances; D008055:Lipids / Q000737:chemistry; D010616:Phenanthrenes / Q000737:chemistry*; D012987:Soil; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D008055:Lipids; D010616:Phenanthrenes; D012987:Soil; D012989:Soil Pollutants; C001861:humin; C031181:phenanthrene