title: [Movement and transformation of nitrate in soil by non-uniform electrokinetics].
abstract: 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.
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Qi-shi
authors.initials: QS
authors.lastname: Luo
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Xi-hui
authors.initials: XH
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Qian
mesh_terms: D004560:Electricity; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009566:Nitrates / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D014867:Water
chemical_list: D009566:Nitrates; D012987:Soil; D014867:Water