土壤有机质对菲的吸附-解吸平衡的影响

以自然土壤和过氧化氢分级土壤为实验模拟样品，测定了菲在这些样品上的吸附一解吸等温线，用线性和Freundlich模型拟合了这些等温线．^13C NMR谱表明，随着土壤有机质腐殖化程度的加深，有机质将含有较多的长链烷烃化合物，含氧、氮化合物有所减少，芳香环的数量变化不大．吸附实验结果表明，土壤有机质含量与菲的吸附容量存在一定的线性相关关系．有机质腐殖质化程度较深的样品比原土壤具有更大的吸附容量，其吸附等温线表现出更为明显的非线性，而且具有更明显的解吸滞后现象．说明土壤中一些结构紧密和含极性官能团较少的有机质是引起菲的非线性吸附过程和解吸滞后现象的主要原因。

Effects of Soil Organic Matters on Adsorption-desorption Equilibria of Phenanthrene

Sorption-desoprtion to natural soil is an underlying process affecting the transport, degradation, and biological activity of hydrophobic organic contaminants(HOCs) in the environment. Mineral fractions and organic matters in soil play important roles in determining the sorption and desorption patterns of hydrophobic organic contaminants. For these contaminants, the mineral fractions of soil play minor roles than organic matter. A study was carried out to determine the relationship between organic matter content and composition of soil and the sorption-desorption of phenanthrene. Hydrogen peroxide was used to reduce the content of soil organic matter(SOM). An examination of soil sample under scanning electron microscope suggested that the pore structure of soil was slightly destroyed amd even 60% of SOM was oxidized. Elemental analysis and solid state ~ ~13 C NMR indicated that the proportion of alkyl C increased, but he proportion of O-alkyl C decreased with reducing the content of SOM. Phenanthrene sorption capacity and isotherm nonlinearity both decreased with increasing the degrees of SOM oxidation, supporting the viewpoint that sorption equlibrium properties of hydrophobic organic contaminants can directly related to the content of SOM. The apparent sorption-desorption hysteresis was quantified for each sample. Sorption-desorption hysteresis index varies from sample to sample, and they also appear to correlate with the chemical characteristics of SOM. The more condensed the soil organic matter is, the more geologically old the soil organic matter is, and the more apparent the sorption-desoprtion hysteresis is. We suggest that the content of SOM is a major determinant of phenanthrene sorption capacity, isotherm nonlinearity and hysteresis.