State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
J Colloid Interface Sci. 2010 Oct 1;350(1):348-54. doi: 10.1016/j.jcis.2010.06.022. Epub 2010 Jun 19.
Binding of hydrophobic organic compounds (HOCs) to humic substances (HS) has significant influence on their fate and bioavailability in an aquatic environment, yet very little is known on the desorption behavior of HOCs in dissolved HS. In this study, triolein-embedded cellulose acetate membranes (TECAMs) were used as passive samplers in dissolved HS-containing solutions to extract the free polycyclic aromatic hydrocarbons (PAHs). The partitioning coefficients (K(OC)) of PAHs in dissolved HS from different sources were determined. Then the rapidly desorbable fractions (f(rd)) of HOCs in dissolved HS were quantified by a quasi-equilibrium model. Results show that the magnitude of K(OC) of PAHs correlated strongly with the O/C atomic ratio and molecular weight of HS. The PAHs with lower K(OW) values desorbed almost reversibly from an aquatic fulvic acid, a sediment humic acid (HA), a lignite HA, and Aldrich HA. However, for strongly hydrophobic chrysene binding to the lignite HA, some extent of desorption resistance was found and attributed to sorption hysteresis as well as steric hindrance. The present study illustrated that the quality of HS and the property of solute may play key roles in determining the desorption reversibility.
疏水性有机化合物（HOCs）与腐殖物质（HS）的结合对它们在水生环境中的命运和生物利用度有重大影响，但对于 HOCs 在溶解的 HS 中的解吸行为知之甚少。在这项研究中，三油酸甘油酯嵌入醋酸纤维素膜（TECAMs）被用作含有溶解 HS 的溶液中的被动采样器，以提取游离多环芳烃（PAHs）。确定了来自不同来源的溶解 HS 中 PAHs 的分配系数（K（OC））。然后通过准平衡模型定量了溶解 HS 中 HOCs 的快速解吸分数（f（rd））。结果表明，PAHs 的 K（OC）大小与 HS 的 O/C 原子比和分子量强烈相关。具有较低 K（OW）值的 PAHs 几乎可以从水生富里酸、沉积物腐殖酸（HA）、褐煤 HA 和 Aldrich HA 中可逆解吸。然而，对于与褐煤 HA 结合的强疏水性苊，发现了一定程度的解吸阻力，这归因于吸附滞后和空间位阻。本研究表明，HS 的质量和溶质的性质可能在决定解吸可逆性方面起着关键作用。
