Effects of DOM on Cr6+ Mobility in Saturated Soil-Water Systems

This study investigated the effects of dissolved organic matter (DOM) extracted form maize straw on the mobility of Cr⁶⁺ in sandy soil and losses widespread in northwest region through simulated dynamic soil column system. The results indicated that the mobility of Cr⁶⁺ was influenced significantly by DOM in saturated water-soil system. Cr⁶⁺ had strong mobility because of weak adsorption and easily to be desorption both in the loess and sand without DOM, and especially in the sandy soil. DOM presence promoted Cr⁶⁺ adsorption in the loess and sand, both the breakthrough time and adsorption capacity to Cr⁶⁺ increased, consequently the mobility of Cr⁶⁺ decreased dramatically. Moreover, when DOM and Cr⁶⁺ were coexistence in the system, both the mobility of them had been weakened. Particle size of loess also effected adsorption of DOM and Cr⁶⁺. Experimental results showed that the adsorption of 60 mesh loess(0.3mm)>;untreated loess>;20 mesh loess (0.9mm). Therefore, it is concluded that the existence of DOM are the main factors that determine the effectiveness of Cr⁶⁺ mobility for decreasing the amounts of soil available Cr⁶⁺ in Cr⁶⁺-contaminated soils. It is very meaningful to prevent and control of ground water pollution.