城市地表径流胶体与溶解性有机物下渗共迁移行为

Co-migration behavior between colloids and dissolved organic matter from urban surface runoff

针对城市地表径流胶体与溶解性有机物(DOM)共存特性,考察下渗柱中径流胶体和DOM的出流浓度,分析进水流速、pH值、离子强度和胶体粒径变化时城市地表径流胶体与DOM的共下渗迁移行为.结果表明,径流胶体与DOM结合后,会显著促进对方向下迁移;进水流速越高,径流胶体对DOM的携带迁移越明显,两者的出流浓度越高;进水流速为10 mL·min^(-1)时,径流胶体和DOM的穿透曲线相对峰值浓度分别比5 mL·min^(-1)时提高了3.5%、8.1%;径流胶体-DOM混合溶液在pH值为6时的下渗共迁移速度最快;Na^(+)存在抑制了径流胶体与DOM的下渗共迁移;共存地表径流胶体粒径越小,DOM的下渗出流时间越早、出流峰值浓度越低.

Aiming at the coexistence of colloids and dissolved organic matter(DOM)from urban surface runoff,the concentrations of runoff colloids and DOM in effluent from the infiltration column were investigated.Besides,the influence of water flow velocity,pH values,Na+concentration and particle size of colloids on the co-migration behavior between colloids and dissolved organic matter were analyzed.The results showed that the combination between runoff colloids and DOM significantly promoted their downward migration.The concentrations of runoff colloid and DOM in effluent were much higher when the influent velocity was higher.Compared to the influent velocity of 5 mL·min^(-1),the relative peak concentrations of the colloids and DOM in effluent were increased by 3.5%and 8.1%under the condition of the influent velocity of 10 mL·min^(-1),respectively.The co-migration speed of the runoff colloids and DOM was the fastest at pH value of 6.The downward co-migration of runoff colloids and DOM was inhibited by the presence of Na^(+).The smaller the particle size of coexisting runoff colloids, the earlier the outflow time of DOM and the lower the peak concentration of DOM in effluent.