Eriksson Johan, Frankki Sofia, Shchukarev Andrei, Skyllberg Ulf
Department of Forest Ecology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
Environ Sci Technol. 2004 Jun 1;38(11):3074-80. doi: 10.1021/es035015m.
The distribution of TNT* (the sum of TNT and its degradation products), aniline, and nitrobenzene between particulate organic matter (POM), dissolved soil organic matter (DOM), and free compound was studied in controlled kinetic (with and without irradiation) and equilibrium experiments with mixtures of POM and DOM reflecting natural situations in organic rich soils. The binding of TNT* to POM was fast, independent of irradiation, and adsorption isotherms had a great linear contribution (as determined by a mixed model), indicative of a hydrophobic partitioning mechanism. The binding of TNT* to DOM was slower, strongly enhanced under nonirradiated conditions, and adsorption isotherms were highly nonlinear, indicative of a specific interaction between TNT derivatives and functional groups of DOM. Nitrobenzene was associated to both POM and DOM via hydrophobic partitioning, whereas aniline binding was dominated by specific binding to POM and DOM functional groups. On the basis of nitrobenzene and TNT* adsorption parameters determined by a mixed Langmuir + linear model, POM had 2-3 times greater density of hydrophobic moieties as compared to DOM. This difference was reflected by a greater (O + N)/C atomic ratio for DOM. The sum of C-C and C-H moieties, as determined by X-ray photoelectron spectroscopy (XPS), and the sum of aryl-C and alkyl-C, as determined by solid-state cross-polarization magic-angle spinning (CP-MAS) 13C NMR, could only qualitatively account for differences in adsorption parameters. Aliphatic C was found to be more important for the hydrophobic partitioning than aromatic C. On the basis of nonlinear adsorption parameters,the density of functional groups reactive with aniline and TNT derivatives was 1.3-1.4 times greater in DOM than in POM, which was in fair agreement with 13C NMR and XPS data for the sum of carboxyl and carbonyl groups as potential sites for electrostatic and covalent bonding. We conclude that in contaminated soils characterized by continuous leaching of DOM, formation of TNT derivatives (via biotic and abiotic reductive degradation) and their preference for specific functional groups in DOM may contribute to a significant transportation of potentially toxic TNT compounds into surface waters and groundwaters.
在反映富含有机质土壤自然状况的颗粒有机物（POM）和溶解土壤有机物（DOM）混合物的控制动力学（有和无辐照）及平衡实验中，研究了三硝基甲苯*（三硝基甲苯及其降解产物的总和）、苯胺和硝基苯在颗粒有机物、溶解土壤有机物和游离化合物之间的分布。三硝基甲苯与POM的结合很快，与辐照无关，吸附等温线有很大的线性贡献（由混合模型确定），表明存在疏水分配机制。三硝基甲苯与DOM的结合较慢，在非辐照条件下强烈增强，吸附等温线高度非线性，表明三硝基甲苯衍生物与DOM官能团之间存在特异性相互作用。硝基苯通过疏水分配与POM和DOM都有关联，而苯胺的结合主要是与POM和DOM官能团的特异性结合。基于由混合朗缪尔+线性模型确定的硝基苯和三硝基甲苯*吸附参数，与DOM相比，POM的疏水部分密度大2 - 3倍。这种差异通过DOM更高的（O + N）/C原子比反映出来。通过X射线光电子能谱（XPS）测定的C - C和C - H部分的总和，以及通过固态交叉极化魔角旋转（CP - MAS）13C NMR测定的芳基 - C和烷基 - C的总和，只能定性地解释吸附参数的差异。发现脂肪族C对疏水分配比芳香族C更重要。基于非线性吸附参数，与苯胺和三硝基甲苯衍生物反应的官能团密度在DOM中比在POM中高1.3 - 1.4倍，这与作为静电和共价键合潜在位点的羧基和羰基总和的13C NMR和XPS数据相当一致。我们得出结论，在以DOM持续淋溶为特征的污染土壤中，三硝基甲苯衍生物的形成（通过生物和非生物还原降解）及其对DOM中特定官能团的偏好可能导致潜在有毒的三硝基甲苯化合物大量运输到地表水和地下水中。
