The sorption of phenathrene by heavy metal-contaminated Changchun water field black soils

Phenanthrene sorption by black soils that have been contaminated by Pb, Zn and Cu was investigated using a batch experimental method. Phenanthrene sorption isotherms by the soil samples with or without the contamination of heavy metals were well described by a linear sorption model with the R2 values greater than 0.92. The distribution coefficients (Kd) and the soil organic carbon-normalized distribution coefficients (Koc) by heavy metal-contaminated soils were significantly higher than those by the control soil. The soil samples contaminated with higher contents of heavy metals manifested the larger sorption coefficients (Kd and Koc). The concentrations of dissolved organic matter (DOM) in equilibrium solution for phenanthrene sorption were observed lower than those by control soil. The less competition for phenanthrene sorption from the decreased DOM contributed little to the enhanced phenanthrene sorption by heavy metal-contaminated soils. But the calculated sorption coefficients of phenanthrene by the DOM sorbed on soil surfaces (KPh/soc) were about 2~3 orders of magnitude larger than the sorption coefficient by the inherent soil organic matters, which we attribute to be the predominant mechanism responsible for the enhanced sorption by the soil samples contaminated with heavy metals.