Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Environ Sci Technol. 2011 May 1;45(9):3996-4002. doi: 10.1021/es2003149. Epub 2011 Apr 6.
Organic matter-mineral interactions greatly affect the fate of hydrophobic organic compounds (HOCs) in the environment. In the present study, the impact of organic matter-mineral interaction on sorption of phenanthrene (PHE) by the original and de-ashed humic acids (HAs) and humin (HM) was examined. After de-ashing treatment, the overall polarity of organic matter in HAs and HM consistently decreased. Differently, the surface polarity of HAs increased but that of HM decreased. No correlation between K(oc) values of PHE by all tested sorbents and their bulk polarity was observed due to inaccessibility of a portion of interior sorption domains. The inaccessibility of interior sorption domains in HAs and HM was partly due to the crystalline structure in organic matter as indicated by differential scanning calorimetric (DSC) and ¹³C NMR data and the interference from minerals. A good correlation between surface polarity of the original and de-ashed HAs and HMs and their K(oc) values for PHE indicated its importance in HOC sorption. Dissimilar changes in surface polarity of HAs and HM after de-ashing treatment can be ascribed to the distinct interactions between organic matter and minerals. The solid-state ¹³C NMR, XPS, and elemental composition data of all tested sorbents revealed that a larger fraction of O atoms in HAs were involved in organic matter-mineral interaction as compared to HM. Results of this work highlight the importance of soil organic matter (SOM)-mineral interactions, surface polarity, and microscaled domain arrangement of SOM in HOC sorption.
有机物质-矿物相互作用极大地影响了疏水性有机化合物（HOCs）在环境中的归宿。本研究考察了有机质-矿物相互作用对原始和脱灰腐殖酸（HA）和腐殖质（HM）吸附菲（PHE）的影响。脱灰处理后，HA 和 HM 中有机质的整体极性持续降低。不同的是，HA 的表面极性增加而 HM 的表面极性降低。由于部分内部吸附域不可接近，因此未观察到所有测试吸附剂对 PHE 的 Koc 值与其体相极性之间存在相关性。HA 和 HM 中内部吸附域的不可接近性部分是由于有机质的结晶结构造成的，这一点可以通过差示扫描量热法（DSC）和 ¹³C NMR 数据以及矿物质的干扰来指示。原始和脱灰 HA 和 HM 的表面极性与其对 PHE 的 Koc 值之间存在良好的相关性，表明其在 HOC 吸附中的重要性。脱灰处理后 HA 和 HM 表面极性的不同变化可归因于有机质与矿物质之间的不同相互作用。所有测试吸附剂的固态 ¹³C NMR、XPS 和元素组成数据表明，与 HM 相比，HA 中更多的 O 原子参与了有机质-矿物相互作用。这项工作的结果强调了土壤有机质（SOM）-矿物质相互作用、SOM 的表面极性和微观域排列在 HOC 吸附中的重要性。
