生态修复网|【专家视角】马杰：污染场地土壤气被动采样技术研究进展马杰1|2|3

马杰1,2,3
1.中国石油大学(北京)化学工程与环境学院，北京102249
2.重质油国家重点实验室，北京102249
3.油气污染防治北京市重点实验室，北京102249
摘要
【生态修复网|【专家视角】马杰：污染场地土壤气被动采样技术研究进展】在VOCs(挥发性有机物)污染场地调查中，土壤气采样的重要性日益受到重视.常规的土壤气采样主要依赖吸附管和采样罐等主动采样方法，但主动采样有很多缺点.作为一种新兴的采样技术，被动采样具有成本低、操作简单、更能代表长时间人体暴露、可用于低渗透性地层等优点，已经成为污染场地调查领域的研究热点.对被动采样的理论基础、采样器类型、吸附剂类型、采样误差的来源进行了介绍，对土壤气被动采样中存在的技术难题以及前沿研究方向进行了讨论，并对该技术在我国场地调查领域的应用前景进行了展望和建议.结果表明：在被动采样中准确控制采样器的采样速率(uptakerate)是保证其定量能力的关键，当控制采样速率低于土壤气中VOCs的补给速率时，可以实现良好的定量效果.影响采样速率的主要因素包括待测VOCs的性质、吸附剂种类、采样器结构以及各类环境因素，挥发性强的VOCs较难被捕集且容易发生逃逸.不同被动采样器用于不同种类VOCs采样时的采样速率可以相差6个数量级，从最低的0.0055mL/min到最高的125mL/min.因此，建议在实际采样中应选用结构合理的采样器，控制采样速率不宜过大，以降低饥饿效应的产生；应选用与待测物匹配的吸附剂，对待测物兼具良好的保留能力和脱附能力；应加强环境因素(温度、湿度、土壤性质)对采样速率影响机制及场地校准方法的研究；应该结合研究和实践经验制定符合我国国情的土壤气被动采样技术指南.
关键词：污染场地；土壤污染；土壤修复；场地调查；风险评估；挥发性有机物；被动采样；土壤气
ResearchProgressonSoilGasPassiveSamplingTechnologyatContaminatedSites
MAJie1,2,3
1.ChinaUniversityofPetroleum-Beijing,CollegeofChemicalEngineeringandEnvironment,Beijing102249,China
2.StateKeyLaboratoryofHeavyOilProcessing,Beijing102249,China
3.BeijingKeyLabofOil&GasPollutionControl,Beijing102249,China
Abstract:Soilgasdataisincreasinglyregardedasanimportantlineofevidenceforthesiteinvestigationandriskassessmentofindustrialsitesimpactedbyvolatileorganiccompounds(VOCs).Conventionalsoilgassamplingapproachreliesonactivesamplingsuchassorbenttubeandcanister,butthesemethodshaveseverallimitations.Passivesamplingisapromisingmethodforsoilgassampling,whichhasseveraladvantagessuchaslowcost,easyimplementation,morerepresentativeforthelong-termhumanexposure,andapplicableforthelowpermeableaquifer.Therefore,passivesoilgassamplinghasbecomeahotresearchtopicintheareaofsiteinvestigationandriskassessment.Thispaperintroducesthetheoreticalbasis,samplers,sorbents,andsamplingerrorsassociatedwithpassivesoilgassampling.CurrenttechnicalchallengesandresearchfrontiersaswellasfutureapplicationofsoilgaspassivesamplingtechniqueinChinaarediscussed.Itisfoundthattheuptakerateisthekeytotheaccuratequantificationofsoilgasconcentrationduringpassivesampling.Keepingtheuptakeratelowerthanthetransportratefromthesurroundingsoiliskeytothesuccessofquantitativemeasurements.KeyfactorsthataffecttheuptakerateincludeVOCs,samplerstructure,sorbentsandvariousenvironmentalfactors.HighlyvolatileVOCsaremoredifficulttobecapturedandmoreeasilytoescapefromsamplersviabackdiffusion.TheuptakerateofdifferentVOCsbydifferentpassivesamplerwouldvaryupto6ordersofmagnitudesfrom0.0055mL/minto125mL/min.Appropriatesamplerwouldhavelowuptakeratetominimizestarvationeffect.Insummary,appropriatesorbentshouldbeexcellentinbothadsorptionanddesorptioncapabilityforthetargetVOCs.Moreresearchesareneededtoimprovecurrentunderstandingoninfluenceofenvironmentalfactors(temperature,humidity,andsoilproperties)onuptakerateaswellasfieldcalibrationmethod.Basedonlaboratoryresearchandfieldexperiences,aguidanceonpassivesoilgassamplingthatissuabletoChinaneedstobeestablished.