title: Characterization of Pb, Cu, and Cd adsorption on particulate organic matter in soil.
abstract: Evidence exists for significant metal enrichment in particulate organic matter (POM) compared to other soil constituents, but the relevant mechanisms are poorly understood. In the present study, adsorption of the heavy metals Pb, Cu, and Cd on a loamy soil and on POM separated from this soil was investigated. The adsorption kinetic data can be well described with a pseudo-second order model, whereas the equilibrium data are well fitted by a Langmuir model. Adsorption isotherms and kinetics data, in addition to the influence of pH on metal adsorption, showed that POM had a much higher adsorption capacity for Pb, Cu, and Cd compared to the whole soil. Ionic strength effects on metal adsorption, Fourier transform infrared spectroscopy, x-ray absorption spectroscopy x-ray absorption spectroscopy including x-ray absorption near-edge structure and extended x-ray absorption fine-structure spectroscopy were employed to elucidate the adsorption mechanisms. The results suggested that Pb and Cu adsorption on POM was mainly through inner-sphere complexes with carboxyl and hydroxyl groups. Cadmium was possibly adsorbed via outer-sphere complexation, indicated by the influence of ionic strength on Cd adsorption.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
authors.forename: Xueyan
authors.initials: X
authors.lastname: Guo
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Zhang
authors.forename: Xiao-Quan
authors.initials: XQ
authors.lastname: Shan
authors.forename: L E I
authors.initials: LE
authors.lastname: Luo
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Pei
authors.forename: Yong-Guan
authors.initials: YG
authors.lastname: Zhu
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Ya-Ning
authors.initials: YN
authors.lastname: Xie
authors.forename: Andrew
authors.initials: A
authors.lastname: Gault
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007854:Lead / Q000737:chemistry*; D009994:Osmolar Concentration; D012987:Soil / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D012987:Soil; D002104:Cadmium; D007854:Lead; D003300:Copper