城市地表径流胶体与溶解性有机物结合特性

为探究城市地表径流胶体与溶解性有机物（DOM）结合特性，考察了不同pH值条件下径流胶体与DOM的吸附行为，并揭示其主要作用机制.结果表明，Langmuir模型可以较好地描述不同pH值时径流胶体对DOM的等温吸附过程，且随pH值增加其最大吸附量逐渐减小，pH值为3.0的最大平衡吸附量是pH值为6.0时的4.0倍；与DOM结合后，径流胶体Zeta电位绝对值升高，胶体更稳定且更易迁移；径流DOM中大分子组分更易与径流胶体结合；径流DOM中疏水酸性组分（HoA）和疏水中性组分（HoN）含量较高，分别占总DOC浓度的35.0%和24.3%，且这两种组分最易与胶体结合；径流胶体和DOM的结合作用主要通过羟基取代、表面络合和静电吸引实现.

Characteristics of the combination between colloids and dissolved organic matter in urban surface runoff

To characterize the combination between colloids and dissolved organic matter (DOM) in urban runoff, the adsorption behaviors of both colloids and DOM under different pH conditions were examined to reveal its mechanisms. The results showed that the Langmuir model described the isothermal sorption of DOM by runoff colloids at different pH values better, and the maximum sorption capacity decreased gradually with an increase in pH. The maximum equilibrium adsorption capacity at pH 3 was 4.0 times more than that at pH 6. The absolute value of zeta potential of runoff colloids increased after adsorption with DOM and then the runoff colloids became more stable and easier to migrate. HoA and HoN are two main fractions in the runoff DOM and account for 35.0% and 24.3% of the total DOC concentration, respectively, and can be combined with runoff colloids most easily, implying that the DOM fractions with high molecular weight are more likely combined with runoff colloids. The combination between runoff colloids and DOM can be achieved through hydroxyl substitution, surface complexation and electrostatic attraction.