土壤中硝酸盐在非均匀电动力学作用下的迁移与转化_罗启仕

土壤中硝酸盐在非均匀电动力学作用下的迁移与转化罗启仕,王慧,张锡辉,钱易(清华大学环境科学与工程系环境模拟与污染控制国家联合重点实验室,北京100084)摘要: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1.0V/cm时,受试土壤中NO-3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NO-3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NO-3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NO-3转化为NO-2,并进一步降低系统的能耗,但不利于土壤中NO-3相对富集.关键词:非均匀电动力学;硝酸盐;电迁移;转化;土壤中图分类号:X53文献标识码:A文章编号:0250-3301(2004)02-0098-06收稿日期:2003-03-26;修订日期:2003-06-30基金项目:日本地球环境产业技术机构资助项目作者简介:罗启仕(1970～),男,博士生,主要从事环境生物修复研究.MovementandTransformationofNitrateinSoilbyNon-uniformElectrokineticsLUOQi-shi,WANGHui,ZHANGXi-hui,QIANYi(EnvironmentalSimulationandPollutionControlStateKeyJointLaboratory,DepartmentofEnvironmentalScienceandEngineer-ing,TsinghuaUniversity,Beijing100084,China)Abstract:Movementandaccumulationofnitrateinsoilandgroundwaterhasbecomeaseriousthreatinmanycitiesandagriculturalareas.Atthesametime,applicationofnitrateasbacterialnitrogenousnutrientinthein-situbioremediationofsomeorganics-pollutedsitesisoftenrequired.Laboratoryexperimentswereconductedtoexaminethefeasibilityofusingnon-uniformelectrokinetics(NUEK)tocontrolthemovementofnitrateinunsaturatedsoil-watersystem.Anaturalsoiltakenfromwoodlandwasusedasexperi-mentalsoil.Threeelectrokineticprocessesweretestedinbench-scalecellsataconstantpotentialgradientof1.0V/cm:unidirectionalNUEK,NUEKwithperiodicpolarity-reversal,andconventionaluniformelectrokinetic(UEK).ThetestsshowedthatNUEKdroveNO-3throughtheexperimentalsoilatarateof13.5～20cm/ddependingupontheconcentrationofNO-3andthedistributionofelec-tricfielddensity.ComparedwithUEK,NUEKprocessmoreeffectivelyconcentratedandretainedNO-3closetotheanode.More-over,NUEKprocessmaintainedsoilcharacteristicsandconsumedmuchlesselectricenergy.ReversalthepolarityofNUEKweakenedtheconcentrationofNO-3toelectrodes,butitstimulatedthetransformationofNO-3toNO-2andfurtherloweredtheelectricenergyconsumption.Keywords:non-uniformelectrokinetics;nitrate;movement;transformation;soil化肥的大量使用以及人畜粪便、城市污水和工业废水的大量排放使土壤和地下水受到硝酸盐的严重污染.在许多城市和农业地区,