PRESENTATION!!!

presentors:MengqianLiuWanqiaoTanTuoZhangBiodegradationof2,4-dichlorophenolinthepresenceofvolatileorganiccompoundsinsoilsunderdifferentvegetationtypesOverview•backgroundofthisresearchpaper•resultsofthisexperiment•possiblereasonfortheresults•howdowevaluethispaper•conclusionbackgroundVOCscanbeutilizedassolecarbonandenergysourcebysoilmicrooganisms(Misraetal,1997).thereareresearchsshowthatmonoterpenecompoundscaninduceorenhancePCBbiodegradation(GilbertES&CrowleyDE,1997.)Thispaperaimstoevaluateeffectsofmonoterpeneamendmentsonthebiodegradationof2,4-dichlorophenolinfreshlyspikedandagedsoil.α-pinene2,4-dichlorophenolacclimationAcclimationofmicrobialcommunitiesutilizeorganiccontaminantsthroughthefollowingthreeways:theinductionofspecificenzymesIncreaseinthenumberofdegradingorganismswiththedesiredmetaboliccapabilities;enhancedmetaboliccapabilitiesthroughgeneticchanges(Spainetal.,1980;Spain&VanVeld,1983;Jensen,1997;Macleod&Semple,2002).MaterialsandmethodspinesoilwithVOCsfreshlyspikedoaksoil××grasssoilwithoutVOCsaged(4weeks)withVOCsamendmentincludes:α-pinene,p-cymeneandmixedVOCS(volumetricratio1:1:1ofα-pinen,p-cymeneandlimonene)materials:methods:uselablled14Ctotracedegradationproductsof2,4-dichlorophenol,14CO2,thenuseNaOHabsorbs14CO2andanalyse.analyticalblank:no[UL-14C]2,4-dichlorophenolblank;sterileblank.Resultsofeachsoiltypesfreshlyspikedsoil•pinesoilhasgreatertotaleffectthanoakandgrasssoil•degradationrateofsterilizesoilaccoutedfor2,4-Dichlorophenolnaturallossagedsoil•pineandoaksoilhavegreatertotaleffectthangrasssoil•maximumrateachievedduringthefirst24hforallsoiltypessignificantdifferencesisbetweensoiltypesratherthantreatments.agedsoildisposalenhancedratesandtotaldegradationcoincidedwithreducedlagtime.grasspineoakfreshagedResultsofeachtreatmentspinesoil•mixedVOCshashighestmax.degradationrateandtotalextentoaksoil•p-cymenehashighestmax.degradationrategrasssoil•p-cymenehashighestmax.degradationratepinesoil•mixedVOCshashighestmax.degradationrateandtotalextentoaksoil•α-pineneandmixedVOCshashigherdegradatonrateandtotalextentgrasssoil•α-pineneandmixedVOCshashigherdegradationrate•freshlyspikedagedgrasspineoakfreshageddiscussion•FreshlyspikedsoilsVSAgedsoil•suggestingthatVOCsareabletoenhance2,4-dichlorophenoldegradationinthese4-week-agedsoils.•Theprecisemechanismforthisenhancementremainsunclear,butitisclearthatbiodegradationisstimulatedbythepresenceofVOCsmainlythroughacclimation.discussion•Possibleexplanationsfortheoveralllowlevelof2,4-dichlorophenoldegradationobservedinbothfreshlyspikedandagedsoilscouldbe:•(1)TherelativelylowpHvaluesforallsoiltypes(Jensen,1997),•(2)Samplesoilscontainlargerquantitiesoforganic/inorganiccarbon,nitrogenandothernutrientslikephosphateandpotassium(Boucard,2004;Kogel-Knabner,2002).commentsAdventagesResultrevealedclearlythatcontamiantedsoiltreatedwithVOCsandacclimulatedforaperiodcanbiogradecontamiantseffectivelyandefficient•applicationofthistechniquehasabrightfutureforsoilremediationShortagesandfutureworks•ThisexperimentsdidnotmeasuretheenhancementofVOCsinquantificationprecisely•DiffrentconcentrationsofVOCsneedstobetriedinfurtherexperiments.•themechanismsofVOCsenhancementneededtobetestedinfurtherexperimentsconclusion•degradationof2,4-dichlorophenolbyindigenousmicroorganismisgreaterinthosesoilsamendedandagedwithmonoterpenes,thaninfreshlyspikedandcontrolledgroup.•remediationsofcontaminatedsoilsmaybepromotedbyjustplantingsomevegetations(eg.pine.)whichcanproducemonoterpenetosoilorjustutilizethenaturalsubstances(eg.pineneedleslitterorcitruswaste)containedrelativehigherconcentrationofmonoterpenes.references•MisraG&PavlostathisSG(1997)Biodegradationkineticsofmonoterpenesinliquidandsoil-slurrysystems.ApplMicrobiolBiotechnol47:572–577.•JensenJ(1997)Chlorophenolsintheterrestrialenvironment.RevEnvironContamToxicol146:25–51.•BoucardTK(2004)Impactandbehaviourofbioactivechemicalsinsoil:implicationsformicrobialfunction.PhDThesis,LancasterUniversity.•Kogel-KnabnerI(2002)Themacromolecularorganiccompositionofplantandmicrobialresiduesasinputstosoilorganicmatter.SoilBiolBiochem34:139–162.•SpainJC,PritchardPH&BourquinAW(1980)Effectsofadaptationonbiodegradationratesinsediment/watercoresfromestuarineandfreshwaterenvironments.ApplEnvironMicrobiol40:726–734.•SpainJC&VanveldPA(1983)Adaptationofnaturalmicrobialcommunitiestodegradationofxenobioticcompounds:effectsofconcentration,exposuretime,inoculumandchemicalstructure.ApplEnvironMicrobiol45:428–435•MisraG,PavlostathisSG,PerdueEM&AraujoR(1996)Aerobicbiodegradationofselectedmonoterpenes.ApplMicrobiolBiotechnol45:831–838.••CarmichaelLM&PfaenderFK(1997)Polynucleararomatichydrocarbonmetabolisminsoils:relationshipstosoilcharacteristicsandpre-exposure.EnvironToxicolChem16:666–675.•HwangS&CutrightTJ(2002)Biodegradabilityofagedpyreneandphenanthreneinanaturalsoil.Chemosphere47:891–899.JensenJ(1997)Chlorophenolsintheterrestrialenvironment.RevEnvironContamToxicol146:25–51.•MacleodCJA&SempleKT(2002)Theadaptationoftwosimilarsoilstopyrenecatabolism.EnvironPollut119:357–364.•ReidBJ,FermorT