土壤中硝酸盐在非均匀电动力学作用下的迁移与转化

以传统的均匀电动力学方法为对照,研究了用非均匀电动力学方法控制土壤中硝酸盐迁移的可行性.结果表明:在外加电压梯度为1.0 V/cm时,受试土壤中NO₃^-在非均电动力学作用下的电迁移速率为13.5～20.0cm/d,并且迁移速率大小与NO₃^-浓度和场强分布有关;与均匀电动力学相比,非均电动力学方法更有利于土壤中NO₃^-向阳极区迁移,而且该方法对土壤性质影响更小,电能消耗更低;切换非均电动力学极性能促使土壤中NO₃^-转化为NO₂^-,并进一步降低系统的能耗,但不利于土壤中NO₃^-相对富集.

Movement and Transformation of Nitrate in Soil by Non-uniform Electrokinetics

Movement and accumulation of nitrate in soil and groundwater has become a serious threat in many cities and agricultural areas. At the same time, application of nitrate as bacterial nitrogenous nutrient in the in-situ bioremediation of some organics-polluted sites is often required. Laboratory experiments were conducted to examine the feasibility of using non-uniform electrokinetics (NUEK) to control the movement of nitrate in unsaturated soil-water system. A natural soil taken from woodland was used as experimental soil. Three electrokinetic processes were tested in bench-scale cells at a constant potential gradient of 1.0 V/cm: unidirectional NUEK, NUEK with periodic polarity-reversal, and conventional uniform electrokinetic (UEK). The tests showed that NUEK drove NO3- through the experimental soil at a rate of 13.5-20 cm/d depending upon the concentration of NO3- and the distribution of electric field density. Compared with UEK, NUEK process more effectively concentrated and retained NO3- close to the anode. Moreover, NUEK process maintained soil characteristics and consumed much less electric energy. Reversal the polarity of NUEK weakened the concentration of NO3- to electrodes, but it stimulated the transformation of NO3- to NO2- and further lowered the electric energy consumption.