【摘要】 选择8种有机质含量各异的土壤,考察其对菲吸附行为的动态变化特征,并利用Freundlich模型描述1、48和720h条件下菲的相分配关系。结果表明,在不同接触时间条件下,Freundlich吸附系数KF与土壤有机质含量呈显著的线性关系,8种土样吸附行为的非线性指数n随时间逐渐减小,经土壤有机碳含量校正的单点Koc*值也随时间上升。这些结果指示土壤有机质是有机污染物土壤吸附的主要汇,土壤有机质吸附位点的位能表现为非均匀分布,颗粒内部有机质吸附位点的容量更大。此外,利用差减方式得到吸附过程后段的相分配关系的非线性明显强于吸附过程前段,说明慢吸附阶段中结构致密的土壤有机质组分的影响更趋强烈疏水性有机污染物在致密有机质组份中的扩散过程很可能是慢反应发生的主要原因。更多还原

【Abstract】 The time-dependent sorption behaviors of phenanthrene on 8 soils with different organic carbon contents were investigated, and the phase distribution relationships at different contacting time of 1 h, 48 h and 720 h were described using Freundlich equation. The experimental data demonstrated that, at different contacting time studied, a significantly linear correlation occurred between the values of the sorption capacity KF and the soil organic carbon contents, the nonlinearity index n gradually decreased, whereas the organic carbon content normalized single-point Koc* values increased for all the soil samples. These results indicate that soil organic matters are the main sink of organic contaminants in soil, and the potential energy of sorption sites in soil organic matters is heterogeneously distributed, and the site capacity of the organic matters inside the soil particles is larger than that outside the soil particles. In addition, by subtracting approach to sorption isotherms, the phase distribution nonlinearity of the slow sorption in the latter section of sorption procedure was significantly higher than that of the fast sorption in the former section of the sorption procedure, which implies that the influence of the condensed organic carbon fractions is much stronger in the slow sorption section, and the diffusion of hydrophobic organic compounds in the condensed organic carbon fractions is probably the main rate-dependent step of the slow sorption.更多还原