Division of Environmental Science and Ecological Engineering, Korea University, Seoul 136-713, Republic of Korea.
Chemosphere. 2010 Jan;78(4):423-9. doi: 10.1016/j.chemosphere.2009.10.055. Epub 2009 Nov 14.
The effect of the sorption of phenanthrene and 2,2',5,5'-polychlorinated biphenyl (PCB52) by five differently weathered soils were measured in water and low methanol volume fraction (f(c)0.5) as a function of the apparent solution pH (pH(app)). Two weathered oxisols (A2 and DRC), and moderately weathered alfisols (Toronto) and two young soils (K5 and Webster) were used. The K(m) (linear sorption coefficient) values, which log-linearly decreases with f(c), were interpreted using a cosolvency sorption model. For phenanthrene sorption at the natural pH, the empirical constant (alpha) ranged between 0.95 and 1.14, and was in the order of oxisols (A2 and DRC)<alfisols (Toronto)<young soils (K5 and Webster). Smaller alpha values for highly weathered soils are indicative of smaller solute sorption reduction than those predicted from the increment of the solute's activity coefficient in the solution phase. A similar trend was observed for PCB52 sorption. The K(m) values measured at the range of pH 3-7 also showed an inversely log-linear relationship. The regression slope (alphasigma) calculated from the cosolvency sorption model as a function of pH(app) only varied within <5%, with the exception for phenanthrene sorption by two highly weathered soils, which had 10% greater alphasigma values obtained at acidic pH(app). This phenomenon is a result of the greater acid enhancement effect on phenanthrene sorption by the oxisols, which is reduced with increasing f(c). These results revealed an unexplored relationship between the cosolvent effect on the sorption and the properties of the soil organic matter (a primary sorption domain) as a function of the degree of soil weathering.
五种不同风化土壤对水中菲和 2,2',5,5'-四氯联苯（PCB52）的吸附作用及其与表观溶液 pH 值（pH(app)）的关系进行了研究。使用了两种风化的氧化土（A2 和 DRC）、中度风化的淋溶土（多伦多）和两种年轻土壤（K5 和 Webster）。K(m)（线性吸附系数）值随 f(c) 的对数线性下降，并用共溶剂吸附模型进行了解释。在自然 pH 值下，菲的吸附 K(m) 值的经验常数（alpha）在 0.95 到 1.14 之间，顺序为氧化土（A2 和 DRC）<淋溶土（多伦多）<年轻土壤（K5 和 Webster）。高度风化土壤的较小 alpha 值表明，与预测的在溶液相中溶质活度系数增加导致的溶质吸附减少相比，溶质的吸附减少较小。对于 PCB52 的吸附，也观察到了类似的趋势。在 pH 3-7 范围内测量的 K(m) 值也显示出反对数线性关系。从共溶剂吸附模型计算的 pH(app)函数的回归斜率（alphasigma）仅在 5%以内变化，除了两种高度风化的土壤对菲的吸附，在酸性 pH(app)下，其 alphasigma 值增加了 10%。这种现象是由于氧化土对菲吸附的酸增强效应更大，而随着 f(c)的增加而减小。这些结果揭示了共溶剂对吸附的影响与土壤有机质（主要吸附域）的性质之间的关系，这是与土壤风化程度有关的。
