: Muhammad Iqbal To cite this version: Muhammad Iqbal. :. Agricultural sciences. AgroParisTech, 2012. English. <NNT : 2012AGPT0020>. <pastel-00811413> HAL Id: pastel-00811413 https://pastel.archives-ouvertes.fr/pastel-00811413 Submitted on 10 Apr 2013 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research ititutio in France or abroad, or from public or private research centers. L archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d eeignement et de recherche français ou étrangers, des laboratoires publics ou privés.
N :2009ENAMXXXX DoctoratParisTech THÈSE pourobtenirlegradededocteurdélivrépar L ItitutdesSciencesetIndustries duvivantetdel Environnement (AgroParisTech) Spécialité: Sciencedel environnement présentéeetsoutenuepubliquementpar MuhammadIQBAL le16mars2012 Impactdel occupationdessolsagricolescontaminéssurladisponibilitédes élémentstrace:miseenévidencedurôledesmatièresorganiquesdale casdeculturesannuellesetculturespérennesàvocationénergétique Jury: M.AlainBERMOND Professeur,AgroParisTech,Paris Président MmeLaurenceDENAIX DirecteurdeRechercheINRA,Bordeaux Rapporteur M.FrancisDOUAY EeignantChercheur,GroupeISA,Lille Rapporteur M.JeanMARTINS ChargédeRecherche,CNRS,Grenoble Examinateur M.ChristopheSCHWARTZ Professeur,UniversitédeLorraine,Nancy Examinateur MmeIsabelleLAMY DirecteurdeRechercheINRA,Versailles DirecteurdeThèse INRAUR251 PESSAC,PhysicochimieetEcotoxicologiedesSolSd'AgrosystèmesContaminés BâtimentdeScienceduSolRD1078026VersaillesCedex,France
Acknowledgements Thisdissertationwouldnothavebeenpossiblewithouttheguidanceandthehelpofseveral individualswhoinonewayoranothercontributedandextendedtheirvaluableassistancein thepreparationandcompletionofthisstudy. The grant for my research work and my stay in France were financed by the Higher EducationCommission(HEC),GovernmentofPakistan.Iwouldliketoextendmythanksto HECinthisregard. Aboveall,IamdeeplygratefultomysupervisorMmeIsabelleLAMYforprovidingmean opportunitytoworkwithher.ifindithardtoimaginethatanyonecouldbeamoresincere, kindandbetterresearchadvisorthanwhatshehasbeen.isabelle,yourthoroughanalysisof myworkandrigorouscritiquenotonlyimprovedmyoverallunderstandingofthesubject butalsothequalityofthisdissertation.yourenthusiasmtowardsscienceandyourpursuitto do goodscience helpedtoshapemyowcientificvalue.thankyouforlisteningmewith patienceandprovidingmewithvaluablesuggestiowhenevericametoyourofficewith myproblems.iwillneverforgetthemomentswepassedtogtherduringdifferentjourneys whichwehadtogetherduringthesethreeyearsfromplacedecomédieofmontpellierto RiverDanubeofViennaandfromfieldsofPierrelayetothesiteofMetaleurop.Iamreally proudofbeingyourstudent. IwouldliketoextendmysincerethankstoMmeLaurenceDENAIX,DirecteurdeRecherche INRA,Mr.FrancisDOUAY,EeignantChercheurGroupeISA,Mr.JeanMARTINS,Chargéde RerchercheCNRS,Mr.ChristopheSCHWARTZ,ProfesseurENSAIA,andMr.AlainBERMOND, ProfesseurAgroParisTechforacceptingtoevaluatemythesiswork. IwouldliketorecordmygratitudeforMr.AlainBERMONDwhoasmycorresponding ProfessoratAgroParisTechhasalwaysbeenkind,andgivencotructiveadvicestocomplete mythesisprojectsuccessfully.thanksalainforyournicesuggestioandhelpfrommy Mastertillthecompletionofthisthesis. Iferventlyextendmyzealousthankstothemembersofmythesiscommittee,Mr.Guillaume MORIN,IMPMCUPMC,MmeAnnetteDEVAUFLEURY,UniversitédeFrancheComtéand MmeChristellePRUVOT,ISAdeLillefortheircotructivecomments,scientificremarksand scholasticguidancewhichhelpedmetocotructandrunthisthesisworkwithgoodquality. IntheseyearsIhavealsobenefitedalotfromtheexteiveknowledgeandmanagerial experienceofourheadofthepessacunit,dr.christianmougin.hehasalwaysbeeo welcomingandsmilingalways.thankyousomuchchristanforyourhelpandguidancein
solvingmymanagerialproblemsduringtheseyearsandforgivingmeaccesstoallfacilities attheunit. ImustacknowledgeandappreciatethesuggestioIhadfromallthescientificstaffof PESSACespeciallyfromFokvanOortandMikaëlHeddeduringallthelabmeetingsoraround theworkingtablesofthelaboratoriesofgroundflooraswellasbasmentofpessac. This work would have never been accomplished without the technical help of all the technicalstaffofunitpessac.theyallhavebeeoniceandhelpingallthetimes.ispecially acknowledgethepersoofoffice106.thanksjeanpierreforhelpingmerightfrommy masterstotheendofphd.iwillrememberthejoywhichwehadtogetherwhilediningat Pakistani and Japanese restaurants of Paris...Thanks for always explaining me French lifestyleandtraditioandgivingthedetailsofflashnewswhichwehadatradiowhile workingaroundthetableinthegrandlaboratory.améliewithoutyourhelpiwouldnever hadtheresultsfromatomicabsorptiopectrophotometertotraformthemintowords forthisthesis.youwasalwayssocooperativeandsmilingevenificametoyoutentimesa daywiththeproblemswiththisapparatus.ialwayslikedyourremarkswheniusedtowork inlaborinofficeandyoualwayscametomewhilepassingbycorridors.thanksforyour throughouthelp.withthehelpofsebastienihavebeenabletocompletemysample preparationandsoilphysicalfractionationwork.thanksalotsebastienforalwaysbeing helpfulandsupportinginmylongexperiments. Specialthankstoplateaudebio,NathalieandChristelle,fortheirhelpinmyworkduringmy bioexperimentsandgivingmeaccesstotheitallatioofthebasementlabsofpessac. ThanksNathalieforyourcooperation,youhavealwaysbeenavailabletohelpevenifyou arealwaysbusyinexperiments.ialwayslikedthemuchnicecakesanddishesyoumade duringthepartiesoftheunit. IamthankfultoAnneJaulinforherhelpregardingatomicabsorptiopectrophotometer andhercommentsduringlabmeetings,jeannechantalforherguidanceregardingstats, NicoleandMehdiforsolvingmyproblemsrelatedtocomputerandsoftware,andAnitaand Célineforalwayshelpingmeinadministrativeworkswithsmilingfaces. Iamimpressedandwillneverforgetthefriendlyenvironmentandworkingrelatiohipsof thewholepessacteam.theyallhavebeeocuriousnotonlytoaskmeaboutmystudies butalsoaboutsituationofmyfamilybackinpakistan.becauseofthisfriendlyenvironmenti neverfeltthatiamawayfrommyfamilyandthesefouryearspassedjustlikeitwasashort moment.iamreallythankfultoallofthem. IamreallygreatefultothenonpermanentmembersofPESSACteamwithwhomIshared eithermyofficeorworkingplaceofthelaboratories.thankstomypresentofficefellows
Benjamin,Léa,SylvainandKevin.Theyallhavebeeoniceandalwayssupportedme especiallyinthisdifficulttimeofthesiswriting.thankstomalika,jeremie,cindy,olivier, Ashref,Shaharm,Stéphanie,Flavie,Fatima,SouadandallotherstudentswithwhomeI workedduringthistimeofthesis. Truegreatfriendsarehardtofind,difficulttoleaveandimpossibletoforget.Iamluckyto havefriendswhosecareandcooperationisverypreciousforme.pierre,iwillalways rememberyournicecompany,careandguidanceineverypersonal,workorfrenchlanguage matter.ienjoyedalottheparisianculturallifewithyouandnadler.cordailthankstoyou bothforhelpingmeespecilallyinmymasterstudies.pierre,iwillespeciallynotforgetmy stayinalsacewithyourfamilyinthecoldchillingweatherofdecemberandtheirmuchnice hospitality.iwishicouldhostyouallonceinpakistan. AspecialthankstomyfriendsKhalid,Ulfat,Rizwan,UmarFarooq,Ahmad,Tahir,Sarfraz, Moeez,ImranandallotherfriendsinFranceforallthememorablemomentsthatwehad sharedtogetherandmademystayinfranceunforgettable. Motto I really lack the words to say you what I want..without your help, support, encouragementandfriendshipiwouldneverhadcompletedthiswork.andneverbeat placewhereiamnow.iseeyoubehindeachwordofthisthesis.shukria. Noacknowledgementscouldeveradequatelyexpressmyfeelingsformyaffectionateand adoringfamily.theyallowedmetocontinuemystudyabroadandgivenmethestrength andcouragetofacetheproblemsoflife.iwillespeciallyacknowledgemysweetgandisister manowhoalwaysremainprayingforme.yehalagbaathakshadikbaadthoribemukhho gaiha...butiamtheoneforwhomshepraysthemostandtakescareof In the end I heartily acknowledge and extend thanks to those whose names are not mentionnedherebuttheycontributedtocompletethiswork... MuhammadIQBAL
Abstract Thechangesinlanduseofagriculturalsoilsaresusceptibletomodifyqualityandquantityof soilorganicmatter.soilorganicmatterisknowntohavearoleoftrophicresourceforsoil organismsaswellastheroleofligandfortracemetalsincontaminatedsoils.changesinthe organicmatterqualityandquantityioilscanleadtowardsmodificationoftracemetal speciationioils.buttheroleofsoilorganicmatterinthedeterminismoftracemetal availabilitiesincontaminatedsoilsisnotwelldocumented.theobjectiveofthethesiswork wastoassesstheroleofsoilorganicmatterindeterminismoftracemetalavailabilitiesin contaminated agricultural soils under annual crop and under perennial energy crop miscanthus.astrategyofstudyingcu,pb,znandcdavailabilitiesoftwositesdifferinginthe soiltextureandoriginofpollutionwasadoptedi.e.thesiteofmetaleurop(northoffrance) withsiltloamsoilscontaminatedbyatmosphericmetalfalloutandthesiteofpierrelaye (ParisRegion)withsandysoilscontaminatedthroughlongtermuntreatedwastewaterinput fromcityofparis.roleoforganicmatterintracemetalavailabilitywasassessedthrough studying;1)thesoilsunderwithtwodifferentlandusesi.e.underannualcropandunder perennial energy crop miscanthus, 2) the soil samples before and after soil organic mineralizationthroughinvitrosoilincubatio,3)thesoilsampleswithandwithoutthe particulateorganicmatter(pom)fractioi.e.themostlabileorganicmatterfractioin ordertohighlightthespecificroleofthisorganicmatterfraction.acombinedapproachof metalavailabilityassessmentthroughchemicalmetalextractioandofstudyingmetal localization in different soil size fractio was used. The results of the trace metal availabilitiesofthesoilundermiscanthuscomparedtoannualcropsoilshowedthatthe influenceofchangesinorganicmatterthroughlandusewasdifferentatbothsites.forthe Metaleurop site, the availability of Cu and Pb which are the metals known to be preferentiallyboundtoorganicmatterwasdecreasedwithanincreaseintheirlocalizationin soilfinerfractio.nochangeintheavailabilityandlocalizationofznandcdwasobserved for this site. Contrarily, in the Pierrelaye site with organic matter rich sandy soils the availabilityofmetalswhichareknowntobeboundtosoilmineralphasesi.e.znandcdwas changedwithoutachangeintheirlocalizationwhilenochangewasobservedforcuandpb. Theresultsofsoilincubatiotudyrevealedthattheeffectofsoilorganicmineralizationon tracemetalavailabilitywassitedependentforpbandcdwhileeffectoncuandznwas similarinallsoilswhateverthesite.ourworkonthemetalenrichedparticulateorganic matterfractioshowedthatpombeingafreeorganicmatterfractionparticipatedinthe metalavailabilityandthatthepomassociatedcopperwasbioavailableforanorganismin our conditio. These results concerning the trace metal availabilities in the soils with varyingnatureandquantityoforganicmatterarediscussed. Keywords:Tracemetals,Cu,Pb,Zn,Cd,availability,contaminatedagriculturalsoils,organic matter,chemicalextraction,granulometricfractionation,pom
Tableofcontents INTRODUCTION...13 Aimsofthethesisresearch... 15 Chapter1:Literaturereview...18 1.1. Tracemetalsandagriculturalsoils... 18 1.2. Factorsaffectingfateoftracemetalsinthesoils... 19 1.3. Soilorganicmatterasalabilesoilcotituent... 23 1.4. Bioavailabilityoftracemetalsconceptsanddefinitio... 35 1.5. Methodsoftracemetalavailabilityassessment... 40 1.6.PotentialofTrametesversicolorasabiomarkeroftracemetalavailabilityassessment 48 Chapter2:Materialandmethods...50 2.1Choiceofsitesandsituatio... 50 2.3 Choiceofmethods... 54 Chapter3:Impactoflanduseontracemetalavailabilitiesincontaminated agriculturalsoils...67 3.1. Introduction... 67 3.2. Results:... 68 3.2.1. 3.2.2. 3.2.3. Influenceoflanduseontracemetalavailabilities... 68 3.2.1.a. 3.2.1.b. 3.2.1.c. 3.2.1.d. EDTAextractablemetalcontentsatequilibrium... 68 DTPAextractablemetalcontentsatequilibrium... 69 NH4NO3extractablemetalcontentsatequilibrium... 71 Kineticallydefinedlabileandslowlylabilemetalfractioandtheir associatedextractionratecotants... 71 3.2.2.a. 3.2.2.b. Influenceoflandusesontracemetallocalizationinphysicalsizefractio:... 75 Massdistributionofthesoilsinthephysicalsizefractio... 75 Distributionoforganiccarbonandtracemetalcontentsinthephysicalsize fractioofthesoils... 76 Relatiobetweeoilmetalavailabilitiesandsoilmetallocalization... 79 3.3. Discussion:... 83 3.3.1. Studyofsoiltracemetalavailabilitiesbythemetalextractionatequilibriumand kineticmetalextractio... 83 3.3.2. Effectoflanduseontracemetalavailabilitiesandmetallocalizationinphysical fractio... 85 3.3.3. Relatiobetweentracemetalavailabilitiesandmetallocalization... 87 3.4. Conclusion:... 89 1
Chapter4:Soilorganicmatterasamainparameterinvolvedinchangesin tracemetalavailabilitiesofcontaminatedagriculturalsoils...91 4.1. Introduction... 91 4.2. Resultsanddiscussion:... 92 4.2.1. Effectofsoilincubationooilorganicmatterandselectedsoilchemicalproperties... 92 4.2.1.a. Mineralizationofsoilorganicmatterduringincubation... 92 4.2.2. 4.2.3. 4.2.1.b. 4.2.1.c. 4.2.1.d. 4.2.2.a. 4.2.2.b. Effectofsoilincubationooilproperties... 94 EffectofsoilincubationonWatersolubleorganiccarboncontents... 94 EffectofsoilincubationopecificUVabsorbanceat420nm(SUVA420)... 95 Influenceofsoilincubationonavailabilityofthetracemetals... 96 thesoils 4.2.2.c. EDTAextractablemetalcontents... 96 DTPAextractableandNH NO extractable(exchangeable)metalcontentsin 4 3... 98 Labileandslowlylabilemetalpoolsandtheirextractionratescotants.. 100 Changesinmass,organiccarbonandtracemetallocalizationindifferentsize fractioduringincubation... 106 4.2.4. 4.2.3.a. 4.2.3.b. 4.2.3.c. Massdistributionindifferentsizefractioofthesoils... 106 Tracemetalsdistributionindifferentsizefractioofthesoils... 108 Distributionoftotalorganiccarboncontentsintodifferentphysicalsize fractioofthesoils... 113 Relatiohipsamongtracemetalavailability,metallocalizationandorganiccarbon distributioninphysicalsizefractio... 117 Metaleurop... 117 Pierrelaye... 120 4.3. Conclusion... 125 Chapter5:Roleofparticulateorganicmatter(POM)fractiointhetrace metalavailabilityioils...126 5.1. Introduction... 126 5.2. ResultsandDiscussion... 127 5.2.1. Effectofsoilincubationonparticulateorganicmatterfractioofthecontaminated soilsamples... 127 5.2.2. 5.2.1.a. 5.2.1.b. Quantityofparticulateorganicmatter(POM)fractiointhesoils... 127 Effectofsoilincubationonmetalenrichmentfactorsofparticulateorganic matterfractio... 128 ComparisonoftracemetalavailabilityoftheannualcropsoilswithPOMfractio andwithoutpomfractio... 130 5.2.2.a. Contributionofparticulateorganicmatterassociatedmetalstototalsoil metalcontentsoftheannualcropsoilsofbothsites... 130 2
5.2.3. 5.2.2.b. 5.2.2.c. EDTAextractablecontentsatequilibrium:... 131 Labileandslowlylabilemetalpoolsandtheirextractionratescotants.. 132 BioavailabilityofcoppertothefilamentousfungiTrametesversicolorinaliquid medium:comparisonofcuaddedintheformofsolutionandcopperlinkedtosoil particulateorganicmatter... 136 5.2.3.a. 5.2.3.b. 5.2.3.c. 5.2.3.d. Evolutionofthefungalbiomassdevelopment... 136 EvolutionofpHintheliquidmediums... 137 Evolutionofthecoppercontentsofliquidculturemediums... 139 Evolutionofthelaccaseactivitiesintheliquidmediums:... 142 5.3. Conclusion... 145 GENERALCONCLUSION...146 LITERATURECITED...151 3
ListofFigures Figure1.1:Majorinputfluxesoftracemetalsintoagriculturalsoils.... 18 Figure1.2:EstimationofannualinputoftracemetalsintoagriculturalsoilsofFrancewith theirprinciplesources.(valuestakenfromsorgreahademe,2007)... 19 Figure1.3:Bioavailabilityprocessesofsoiltracemetalpartitioningbetweeoilsolidand solutionphasesincludingspeciationioilsolutionanhowtheycanbeinfluencedby soilpropertiesandenvironmentalconditio.(reproducedfromhooda,2011)... 37 Figure1.4:TracemetalbioavailabilityinthesoilsasdescribedbynormeISO17402(ISO, 2008)... 39 Figure1.5:Timemetalextractionexperimentalcurve(Right)andacurveobtainedbydata modeling(left)bytwofirstorderreactionmodel... 47 Figure2.1:MapofexperimentalsiteMetaleurop... 50 Figure2.2:MapofexperimentalsitePierrelaye... 51 Figure2.3:Schematicdiagramofvariousstepsoftracemetalextraction... 55 Figure2.4:Schematicdiagramofvariousstepsofphysicalfractionationofsoils... 57 Figure2.5: SchematicdiagramofvariousstepsofCO2measurementduringsoilincubation andmaintenanceofsoilmicrocosms... 58 Figure2.6:Schematicdiagramofvariousstepsofsolubleorganiccarbonextraction... 60 Figure 2.7a: Schematic diagram of various steps followed to prepare soil samples with particulateorganicmatter... 61 Figure2.7b:Schematicdiagramofvariousstepsfollowedtopreparesoilsampleswithout particulateorganicmatter... 61 Figure2.8:Schematicdiagramofthebiotestforstudyingtracemetalavailabilitybyusing fungalcultures... 63 Figure3.1:NH NO extractablemetalcontentsofthesoilsbeforeandaftersoilincubation. 4 3 Bar graphs represent mean values of 3 replicates while the error bars represent standard deviation among these replicates. Different letters indicate statistically significantdifference(tukey stest,p<0.01)ofmetalextractabilitybetweenannualcrop andmiscanthussoilforeachsite.... 70 Figure3.2:Percentagesoflabilemetalfraction(Q ),slowlylabilemetalfraction(q )ofthe 1 2 soilsamplesofpierrelaye.bargraphsrepresentmeanvaluesof5replicateswhilethe 4
error bars represent standard deviation among these replicates. Different letters indicatestatisticallysignificantdifference(tukey stest,p<0.01)betweenannualcrop andmiscanthussoilforeachfraction.... 73 Figure3.3:Distributionofthesoilmassintodifferentphysicalsizefractioofthesoilsof Metaleurop(a)andPierrelaye(b).Bargraphsrepresentmeanvaluesof3replicates whiletheerrorbarsrepresentstandarddeviationamongthesereplicates.statistically significantdifference(tukey stest,p<0.05)betweenannualcropandmiscanthussoil foragivenfractionisshowedbydifferentletterswhile representnoignificant differences.... 75 Figure3.4:Distributionofthesoiltracemetalandorganiccarboncontentsintodifferentsize fractio of the soils of Metaleurop site. Curves represent the organic carbon distributionindifferentfractio.bargraphsrepresentmeanvaluesof3replicatesfor metal distribution while the error bars represent standard deviation among these replicates.statisticallysignificantdifference(tukey stest,p<0.05)ofmetaldistribution betweenannualcropandmiscanthussoilforagivenfractionisshowedbydifferent letterswhile representnoignificantdifferences.fororganiccarbondistribution thestatisticallysignificantdifferenceisshownbythesign(*)... 77 Figure3.5:Distributionofthesoiltracemetalandorganiccarboncontentsintodifferentsize fractioofthesoilsofpierrelayesite.bargraphsrepresentmeanvaluesof3replicates for metal distribution while curves present the organic carbon distribution these fractio. The error bars represent standard deviation among these replicates. Statisticallysignificantdifference(Tukey stest,p<0.05)betweenannualcropand miscanthussoilforagivenfractionisshoweddifferentletterswhile representnon significantdifferences.... 78 Figure4.1:Evolutioninthemineralizationoforganicmatterofthesoilswiththetimeof incubation(expressedaspercentageofinitialsoilorganiccarboncontents).curves represent mean values of three replicates while error bars represent standard deviatio.... 93 Figure4.2:Watersolubleorganiccarboncontents(a)andSUVA (b)ofthesoilsamples before and after soil incubation. Data is presented on soil dry weight basis. The statistically significantdifference (Tukey s test, p < 0.01) for watersoluble organic carboncontentsandsuva ofeachsoilbeforeandafterincubationispresentedby 420 differentletters.... 94 Figure4.3:EDTAextractablemetalcontents(atequilibrium)ofthesoilsbeforeandafter incubation. Bar graphs represent mean values of 5 replicates while the error bars representstandarddeviationamongthesereplicates.statisticallysignificantdifference 420 5
(Tukey stest,p<0.01)forthemetalcontentsforeachsoilbeforeandafterincubationis representedbydifferentletterswhile representnoignificantdifferences.... 97 Figure4.4:DTPAextractablemetalcontentsofthesoilsbeforeandaftersoilincubation.Bar graphsrepresentmeanvaluesof3replicateswhiletheerrorbarsrepresentstandard deviationamongthesereplicates.statisticallysignificantdifference(tukey stest,p< 0.01) for extractable metal contents for each soil before and after incubation is representedbydifferentletterswhile representnoignificantdifferences.... 99 Figure4.5:NH NO extractablemetalcontentsofthesoilsbeforeandaftersoilincubation. 4 3 Bar graphs represent mean values of 3 replicates while the error bars represent standarddeviationamongthesereplicates.statisticallysignificantdifference(tukey s test,p<0.01)forextractablemetalcontentsforeachsoilbeforeandafterincubationis representedbydifferentletterswhile representnoignificantdifferences.... 100 Figure4.6:Labilemetalfraction(Q )andslowlylabilemetalfraction(q )ofthesoilsamples 1 2 beforeandafterincubation.bargraphsrepresentmeanvaluesof5replicateswhilethe errorbarsrepresentstandarddeviationamongthesereplicates.statisticallysignificant difference(tukey stest,p<0.01)forthemetalcontentsforeachsoilbeforeandafter incubation is represented by different letters while represent non significant differences.... 102 Figure4.7:Distributionofthesoilmassintodifferentphysicalsizefractioofthesoilsof Metaleuropsitebeforeandafterincubation.Bargraphsrepresentmeanvaluesof3 replicateswhiletheerrorbarsrepresentstandarddeviationamongthesereplicates. Statisticallysignificantdifference(Tukey stest,p<0.05)forthemassofagivenfraction before and after incubation of the soils is showed by different letters while representnoignificantdifferences... 107 Figure4.8:Distributionofthesoilmassintodifferentphysicalsizefractioofthesoilsof Pierrelayesitebeforeandafterincubation.Bargraphsrepresentmeanvaluesof3 replicateswhiletheerrorbarsrepresentstandarddeviationamongthesereplicates. Statisticallysignificantdifference(Tukey stest,p<0.05)forthemassofagivenfraction before and after incubation of the soils is showed by different letters while representnoignificantdifferences... 107 Figure4.9:Distributionoftracemetalsinthedifferentphysicalsizefractioofthesoilsof Metaleurop before and after incubation. Bar graphs represent mean values of 3 replicateswhiletheerrorbarsrepresentstandarddeviationamongthesereplicates. Statisticaldifference(Tukey stest,p<0.05)forthemetalpercentageinthefractio before and after incubation of the soils is showed by different letters while representnoignificantdifferences... 110 6
Figure4.10:Distributionoftracemetalsinthedifferentphysicalsizefractioofthesoilsof Pierrelayebeforeandafterincubation.Bargraphsrepresentmeanvaluesof3replicates whiletheerrorbarsrepresentstandarddeviationamongthesereplicates.statistical difference(tukey stest,p<0.05)forthemetalpercentageinthefractiobeforeand afterincubationofthesoilsisshowedbydifferentletterswhile representnon significantdifferences.... 112 Figure4.11:Distributionoforganiccarboninthedifferentphysicalsizefractio.Bargraphs representmeanvaluesof3replicateswhiletheerrorbarsrepresentstandarddeviation amongthesereplicates.statisticaldifference(tukey stest,p<0.05)fororganiccarbon percentage in the fractio before and after incubation of the soils is showed by differentletterswhile representnoignificantdifferences.... 114 Figure5.1:Massoffineandcoarseparticulateorganicmatterfractioofthesoilsbefore andafterincubation.bargraphsrepresentmeanvaluesof3replicateswhiletheerror bars represent standard deviation among these replicates. Statistically significant difference(tukey stest,p<0.05)forthemassofagivenfractionbeforeandafter incubationofthesoilsisshowedbydifferentletterswhile representnoignificant differences.... 127 Figure5.2:Tracemetalcontentsoftheparticulateorganicmatterfractiooftheannual cropsoilsaspercentageoftotalsoilmetalcontents... 130 Figure 5.3: EDTA extractable metal contents of the annual crop soil of both sites at equilibrium.bargraphsrepresentmeanvaluesof3replicateswhiletheerrorbars represent standard deviation among these replicates. Different letters indicate statistically significant difference (Tukey s test, p < 0.01) in the extractable metal contentsofthesoilswithandwithoutparticulateorganicmatter(pom)... 131 Figure5.4:Percentagesoflabilemetalfraction(Q ),slowlylabilemetalfraction(q )ofthe 1 2 annualcropsoilsforthetwositeswithandwithoutparticulatesoilorganicmatter (POM).Bargraphsrepresentmeanvaluesof5replicateswhiletheerrorbarsrepresent standarddeviationamongthesereplicates.statisticallysignificantdifference(tukey s test,p<0.01)foreachmetalfractionofthesoilswithandwithoutpomisindicatedby differentletterswhile representnoignificantdifferences.... 132 Figure5.5:EvolutioninthebiomassofTrametesversicolorexposedtodifferentsourceof copperduringlaboratoryincubatioinliquidmedium... 137 Figure5.6:EvolutioninthepHofliquidmediumbecauseoftheactivityofTrametesversicolor exposed to different source of copper during laboratory incubatio in the liquid medium... 138 7
Figure5.7:PercentageofCuaccumulationinfungiduringlaboratoryincubationinliquid mediumswithcucontaminationaddedascus0 (100µg/L)andasCulinkedtoPOM fractio(50200µm).... 140 Figure5.8:LaccaseactivitiesofTrametesversicolorinliquidmediumexposedtodifferent sourceofcopperduringlaboratoryincubatiointheliquidmedium... 143 4 8
Listoftables Table1.1:Metalenrichmentfactorsoftheparticulateorganicfractioofsomesoils.... 28 Table2.1:Selectedphysicochemicalcharacteristicsofthesoilsamples.Datapresentedis expressedooildryweightbasis.... 53 Table2.2:Compositionoftheliquidculturemediumusedforthebiotest... 64 Table3.1:EDTAextractablemetalcontents(atequilibrium)ofthesoilsamples.Meanvalues of3replicateswithstandarddeviationamongthesereplicates.differentlettersindicate statisticallysignificantdifference(tukey stest,p<0.01)betweenannualcropand miscanthussoilofeachsite... 68 Table3.2:DTPAextractablemetalcontentsofthesoilsbeforeandaftersoilincubation. Meanvaluesof3replicateswithstandarddeviationamongthesereplicates.Different letters indicate statistically significant difference (Tukey s test, p < 0.01) of metal extractabilitybetweenannualcropandmiscanthussoilforeachsite... 69 Table3.3:Percentagesoflabilemetalfraction(Q1),slowlylabilemetalfraction(Q2)ofthe soilsamplesandthecorrespondingextractionratecotantsofthesefractiok1and K2respectivelyforthesoilsofMetaleurop.Meanvaluesof5replicates±standard deviation.differentletterswithineachcolumnindicatestatisticallysignificantdifference (Tukey stest,p<0.01)betweenannualcropandmiscanthussoilforthemetalfractio (Q1andQ2)andtheextractionratecotantsthesemetalfractio(K1andK2)foreach metal.... 72 Table3.4:Extractionratecotantsoflabilemetalfraction(K )andofslowlylabilemetal fraction(k )ofthesoilsamplesofpierrelaye.meanvalues±standarddeviation(n=5). 2 Differentlettersinthecolumindicatestatisticallysignificantdifference(Tukey stest, p<0.01)betweenannualcropandmiscanthussoilfortheratecotantofeachfraction foreachmetal.... 74 Table 3.5: Correlationmatrix (Pearson correlation coefficients) among metal availability parametersi.e.totaledtaextractablecontents(exedta),kineticallydefinedlabile metalfraction(q1),slowlylabilefractio(q2),dtpaandnh4no3extractablemetal contentsandthemetalandorganiccarbondistributionamongdifferentphysicalsize fractioofthesoilsofmetaleuropsite(n=6;valuesinboldaredifferentfrom0witha significancelevelp<0.05... 80 Table 3.6: Correlationmatrix (Pearson correlation coefficients) among metal availability parametersi.e.totaledtaextractablecontents(exedta),kineticallydefinedlabile metalfraction(q ),slowlylabilefractio(q ),DTPAandNH NO extractablemetal 1 2 4 3 contentsandthemetalandorganiccarbondistributionamongdifferentphysicalsize 1 9
fractioofthesoilsofpierrelayesite(n=6;valuesinboldaredifferentfrom0witha significancelevelp<0.05... 82 Table3.7:Summaryoftheresultsofcomparisonoftracemetalavailabilitiesbetweenannual cropandmiscanthussoilsstudiedbyusingdifferentmethodsandextractants.thesig aftermetalsymbolspresentthetrendofchangeinmetalavailabilitiesinthesoilsunder miscanthuscomparedtoannualcropsoils(increase,decrease,nochange)... 84 Table 3.8: Summary of the correlatio between trace metal availabilities and their distributioninphysicalsizefractio.thesigassociatedwithchemicallyextracted metalfractiogivethetypeofcorrelatio(positivecorrelation+,negativecorrelation )whilethefractiounderlinearethesoilphysicalsizefractiowithwhichthemetal availabilitiesarecorrelated... 88 Table 4.1: Selected chemical characteristics of the soil samples before and after soil incubation.dataispresentedooildryweightbasis.wherepresentthedifferent lettersiuperscriptshowthestatisticallysignificantdifference(tukey stest,p<0.01) ofdifferentcharacteristicsforeachsoilbeforeandafterincubation.... 93 Table4.2:Extractionratecotantsoflabilemetalfraction(K )andofslowlylabilemetal fraction(k )ofthesoilsamplesbeforeandafterincubation.meanvalues±standard 2 Deviation (n=5). Different letters in the colum indicate pairwise statistically significantdifference(tukey stest,p<0.01)fortheratecotantsofthemetalsfor eachsoilbeforeandafterincubation.... 103 Table4.3:Summaryoftheresultsofchangesintracemetalavailabilitiesaftersoilincubation studiedbyusingmetalextractionatequilibriumandkineticmetalextractio.where forextractioatequilibriumext1=edta,ext2=dtpa,ext3=nh NO andforkinetic extractioq =labilepool,q =slowlylabilepool,k =Extractionrateoflabilepooland 1 2 1 K =Extractionrateofslowlylabilepool.Thesiginfrontofmetalspresentthetrendof 2 changeinmetalavailabilitiesinthesoilsafterincubationcomparedtothesoilbefore incubation(increase,decrease,nochange)... 104 Table4.4:Percentageofmassrecoveryafterphysicalfractionationofthesoilsbeforeand aftersoilincubation... 108 Table4.5:Percentageofmetalrecoveryafterphysicalfractionationofthesoilsbeforeand incubation... 114 Table4.6:Summaryoftheresultsofchangesintracemetalandorganiccarbondistribution 1 4 3 inphysicalsizefractioofthesoilsafterincubation.wheref =020µm,F =2050µm, 1 2 F =50200µm,andF =2002000µmfraction.Thesiginfrontoffractioshowthe 3 4 trendofchangeindistributioninthesoilsafterincubationcomparedtothesoilbefore incubation(increase,decrease,nochange)... 115 10
Table 4.7: Correlation matrix (Pearson correlation coefficients) among Cu availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), slowlylabilefractio(q ),NH NO,DTPAextractableandtheCuandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofmetaleuropsite(n=6; boldnumbersareforp<0.05).... 118 Table 4.8: Correlation matrix (Pearson correlation coefficients) among Pb availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), slowlylabilefractio(q ),NH NO,DTPAextractableandthePbandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofmetaleuropsite(n=6; boldnumbersareforp<0.05).... 118 Table 4.9: Correlation matrix (Pearson correlation coefficients) among Zn availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), slowlylabilefractio(q ),NH NO,DTPAextractableandtheZnandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofmetaleuropsite(n=6; boldnumbersareforp<0.05).... 119 Table 4.10: Correlation matrix (Pearson correlation coefficients) among Cd availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), slowlylabilefractio(q ),NH NO,DTPAextractableandtheCdandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofmetaleuropsite(n=6; boldnumbersareforp<0.05).... 120 Table 4.11: Correlation matrix (Pearson correlation coefficients) among Cu availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), slowlylabilefractio(q ),NH NO,DTPAextractableandtheCuandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofpierrelayesite(n=6; boldnumbersareforp<0.05).... 121 Table 4.12: Correlation matrix (Pearson correlation coefficients) among Pb availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), slowlylabilefractio(q ),NH NO,DTPAextractableandthePbandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofpierrelayesite(n=6; boldnumbersareforp<0.05).... 122 Table 4.13: Correlation matrix (Pearson correlation coefficients) among Zn availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), slowlylabilefractio(q ),NH NO,DTPAextractableandtheZnandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofpierrelayesite(n=6; boldnumbersareforp<0.05).... 123 Table 4.14: Correlation matrix (Pearson correlation coefficients) among Cd availability parametersi.e.totaledtaextractablecontents(exedta),labilemetalfraction(q ), 1 1 1 1 1 1 1 1 11
slowlylabilefractio(q ),NH NO,DTPAextractableandtheCdandorganiccarbon 2 4 3 distributionamongdifferentphysicalsizefractioofthesoilsofpierrelayesite(n=6; boldnumbersareforp<0.05).... 123 Table 5.1: Metal enrichment factors of the fine and coarse particulate organic matter fractioofthesoils.meanvalues±standarddeviationof3replicates.differentletters indicatethestatisticallysignificantdifference(tukey stest,p<0.05)forthemetal enrichmentfactorsinthepomfractiobeforeandaftersoilincubation.... 129 Table5.2:Extractionratecotantsoflabilemetalfraction(K )andofslowlylabilemetal fraction (K ) of the soil samples with and without POM. Mean values ± Standard 2 Deviation (n=5). Different letters in the colum indicate pairwise statistically significantdifference(tukey stest,p<0.01)forratecotantoflabileandslowlylabile fractioofthemetalsforeachsoilwithandwithoutpom.... 133 Table5.3:Evolutionofthecopperconcentratiointheliquidmediumsduringtheexposure of Trametes versicolor to different source of copper contamination in laboratory incubatio.... 139 1 12
INTRODUCTION Contextofthestudy Asweenterthe21stcenturywithmorethan6.5billionworldpopulation,theworld s soilsneedtobesustainablymanagedtomeetincreasingdemandsincluding:increasedfood production,biomassproduction,restorationofdegradedlands,csequestration,increased resourceuseefficiencyinagriculture,andpreservationofbiodiversity(lal,2009).butatthe sametimeincreasedindustrializationandurbanizationtomeetthebasicnecessitiesof humanbeinghavecreatedachallengethroughstronganthropogenicperturbatioofsoil andenvironment.onetypeoftheseperturbatioistheelevatedlevelsoftracemetalsin thesoils.tracemetalsaredefinedasmetalsinnaturalmaterialsataconcentrationlower than 1000 mg kg 1 (KabataPendias and Pendias, 2001). Some of the trace metals are essentialforbiologicallifebutcanbetoxicatelevatedlevels;othersarenonessentialand canalsobetoxic.themajorchallengeincaseofsoiltracemetalcontaminationisthatthe tracemetalsarenondegradableandpersistioils.elevatedlevelsoftracemetalsnotonly causetoxicitytothesoilorganismsbutcanalsocauseserioushumanhealthhazardsby enteringthefoodchainviaplantuptakeinagriculturalsoils(ramade,2007). Despiteadvancementsicienceandtechnologies,removalofmetalpollutionfrom soilsisneithereffectivenoreasy,particularlyforagriculturalsoilswheremetalpollution levels are lower than in former industrial sites (Dickion, 2000). Sustainable use of contaminatedagriculturalsoilsshouldthusrequiremanagementinawaythatthepotential risksoftracemetalsareminimizedinparticularthroughplantuptakeifalimentarycropsare tobemaintained,oringeneralthroughsoilfunctioning.assessmentoftotalsoilmetal contentsistheinitialsteptowardsriskassessmentbutmainconcernisthedeterminationof metalfractiowhichareavailabletointeractwithsoilecologicalreceptors(harmsen, 2007).Thesemetalfractioconcernthe soilmetalsupply orthe tracemetalavailability asnamedintherecentnormiso17402aimingtodefinethebioavailabilityconcept(iso, 2008).Itiswellknownthatmetalavailabilityioilsisrelatedtosoilmetalspeciationwhich depends on many factors like the type of soil or the soil physicochemical conditio (Bermondetal.,1998).Soilbeingacomplexmediumtheassessmentofmetalspeciationis difficultandmeasurementoftracemetalavailabilityaswellasknowledgeofitsdeterminism 13
isstillachallenge.differentchemicalmethodsareusedtoassessmetalavailabilityioils butthereisstillnoonegenerallyacceptedmethodallowingcomparisobetweetudies. Amongthedifferentsoilcotituentssoilorganicmatterisalabilecotituentand remaiundercontinuouschangeduetodifferentturnoverofitsfractiovaryingfrom plantdebristodissolvedorganicmolecules.incaseofnoncontaminatedsoilconditiothe roleofsoilorganicmatterondifferentsoilpropertiesandooilfunctioninghasbeenan importantfocusofsoilresearchers.itisthuswellestablishedthewaythesoilorganicmatter affectssoilphysicochemicalandbiologicalcharacteristics(ekwue,1990;hussainetal., 1999;Lal,2009).Incaseofcontaminatedsoilsthesoilorganicmatterstillhasaroleasa trophicresourcefororganismsbutfurthermoreactsasaligandformetals.sothenature andquantityofsoilorganicmattercanplayanimportantroleinthedeterminismoftrace metalavailabilityincontaminatedagriculturalsoils.thereactivityandaffinityfortrace metalsofdifferentindividualsoilorganicmatterfractiohasbeenreportedinliterature (Sauvéetal.,2000;Kalisetal.,2006;Sebastiaetal.,2008).Buttheexistenceofalarge number of varieties of organic materials in the soils and the inability to completely characterizesoilorganicmattermakedifficulttoassessitsroleintracemetalavailability. Such a role has been often described in the case of new exogenous organic matter introducedintocontaminatedsoilsasamendmentslikesewagesludgeorcomposts,then assessingtheimpactontracemetalavailability(udometal.,2004;torriandlavado,2008; Smith,2009;Ingelmoetal.,2011).Butrarerarestudiesconcerningchangesinindigenous soilorganicmatterstatus,duetoachangeinlanduseormanagementpracticesratherthan additionofexogenousorganicmatter,ontracematteravailabilities.suchstudieswillbe useful,however,inthenextfuturetobringelementsofawertothechangesofcultural practices,particularlyinthecaseofmetalcontaminatedagriculturalsoilsthevocationof whichtoproducefoodculturesisquestioned. Moregenerally,effectsofchangesinlanduseormanagementpracticesonmaioil propertieslikeph,soilorganicmatterqualityandquantity,orcationexchangecapacityare wellreportedintheliterature(rossetal.,1999;sixetal.,2000;dillyetal.,2003).in contaminatedagriculturalsoilssuchmodificatioioilphysicochemicalconditioare expectedtoinducechangesinmetalspeciation,butthewaythesechangeswilloccurare notalreadyknown.thecoequenteffectsonthesoiltracemetalavailabilitiesarethen 14
difficult to predict. This will be particularly true in the case of changes from annual alimentarycropstoperennialnonalimentarycropslikebioenergycropsassuggestedfor marginallands(campbell,2008;gopalakrishnanetal.,2009),wheretheeffectsduetonon tillagewilladd. In this work the need to assess the impact of the adopted practices for the sustainablemanagementofcontaminatedagriculturalsoilsonthesoilorganicmatterand theresultingeffectontracemetaldynamicsioilshadbeenappliedtotheknowledgeof thechangesintracemetalavailabilities. Theworkpresentedheretookbenefitsfromtwoscientificprogramsdevelopedin thepessacresearchunit:ananrcesresearchproject(agencenationaldelarecherche Contaminants, Environnement et Santé named RESACOR (REconversion des Sols AgricolesContaminés:impactdesculturesàvocationénergétiquessurlabiodisponibilité desélémentstracesetlarelationaveclarépoedesorganismesdusol)andaninsu EC2CO(ItitutNationaldesSciencesdel Univers,)researchprojectnamed MOBIPOCu (Rôledelamatièreorganiqueetdelabiocénosedaledevenird unepollutionchronique etdiffuseaucuivredauolviticole).intheseprojectsconcerningmetalcontaminated soils,theobjectivesweretoassesstheimpactsooilpropertiesofchangesfromannual alimentarycropstoperennialmiscanthusnonalimentarycrop,andthespecificroleofsome soilorganicfractiointracemetalbioavailability.inthepresentworkfocuswasmadeon theavailabilitypartofthebioavailability,i.e.thecharacterizationandtheknowledgeofthe determinismofthetracemetalsoilsupply,aswellastheroleofaspecificfractionofthesoil organicmatter:theparticulateorganicmatters,appliedinthecaseschoseninaccordance withthesedifferentprojects. Aimsofthethesisresearch Inthiscontextthemainobjectiveoftheworkpresentedinthisthesiswastoassess theeffectsofmetalcontaminatedlandusesonthesoiltracemetalsavailabilityusingiitu contaminated soil samples and acombination of laboratory experiments. We chose to comparetwolandusesinthespecificcaseofsoilscultivatedeitherunderannualalimentary cropsorunderperennialmiscanthuscrop.wealsochosetocomparetwositeswhichmainly differ in their soil texture but also in the origin of metal pollution. But for a given 15
contaminated site we made comparison iide the same cultivated parcel where the changesinlanduseoccurred(annualversusmiscanthuscrops).themainhypothesiswe madeconcerntheroleofboththesoiltextureandoriginofthepollution(mainlywheites arecompared)andofthesoilorganicmatter(foragiveite,betweeoilunderannualor perennialcrops,butalsoinourcasewheitesarecompared).thustheexperimental designofsoilsamplingwasusedinordertoassessboththedeterminismoftracemetal availabilitiesandtohighlightthespecificeffectofsoilorganicmatterwhencoupledwith laboratoryexperiments. Thethesisworkthusfocusesonthreeparts: 1) Inafirstpart(chapter3)weaimedatassessingiituforagiventypeofsoilthe effecttocultivateacontaminatedparcelintwodifferentways(annualvsperennial miscanthuscrop)ontracemetalavailabilities.wehypothesizedi)thatchangesioil organicmatterstatusduetochangesioiluseaswellastheabsenceorpresenceof tillagewillaffectthetracemetalavailabilities,andii)thatthisimpactwilldependon thesoiltexture. 2) Inasecondpart(chapter4)wemadecomplementarylaboratoryinvestigatioto assessthepotentialroleoforganicmatterapartoftheeffectofpresenceofabsence oftillage.forthat,wehypothesizedthatanevolutioninthesoilorganicmatter status between soil samples (under annual vs miscanthus perennial crop and between soils of different textures) will affect differently their trace metal availabilities.forthatweenhancedthemineralizationofthesoilorganicmatterof eachsoilsamplethroughinvitrosoilincubatioandassessedtheresultingeffecton soiltracemetalavailabilities 3) Inathirdpart(chapter5)wefocusedonthemostlabilesoilorganicmatterfraction, theparticulateorganicmatters,inordertoassesstheirpotentialroleinthetrace metalavailabilities.weaimedtoassessi)whetherparticulateorganicmatterplaysa roleofsourceorsinkoftracemetalsioils,linkedtothetracemetalavailabilities andii)towhatextentthemetalsassociatedwiththisorganicmatterfractionare bioavailable,ascanbeseenusingabiotest. 16
Finally,thisthesisstudyisarticulatedintofivechapters.Thefirstchapterpresentsa reviewofourpresentknowledgeonthefateoftracemetalsinthesoils,thesoilorganic matter and its affinity towards trace metals and the various concepts of trace metal availabilityandthewaysofitsassessment.inthesecondchapterwepresentallthematerial andmethodsusedinthiswork.thethreefollowingchaptersarebasedontheresults obtainedduringthethesisworkcorrespondingtothethreespecificaimsofthestudy. 17
1.1. Tracemetalsandagriculturalsoils Chapter1 LiteratureReview Tracemetals(TMs)arenaturallypresentioils,thesocalledpedogeochemical backgroundlevelsreflectingtheoccurrenceoftracemetalsinthesoilparentmaterial.with theincreasedindustrializationandurbanization,atremendousamountofthesemetalsis addedtosoilsandwaterenvironmentannuallyfromdifferentsources(figure1.1).infrance e.g.accordingtoanassessmentpublishedin2007atotalof4869toyear 1 ofcu,696to year 1 ofpb,15190toyear 1 ofznand54toyear 1 ofcd(figure1.2)areaddedtothe soilsfromdifferentanthropogenicsources(sorgreahademe,2007).becauseoftheirnon biodegradationandpersistenceinthesoils,thetracemetalsarecoideredtobepotential environmental contaminants for the biological life. The pollutant activities lead to an irreversibleanddiffusivecontamination(contaminationfromaremotee.gvehiclesexhausts, heatingplants,wastewaterirrigationetc)inthelongterm,beinglikelytocompromisethe fertilityandthequalityoftheagriculturalsoils(chassinetal.,1996;ramade,2007).in additiontothesediffusivecontaminatio,localindustrialandurbanexploitatiocanalso cause soil contamination (e.g. case of Metaleurop in the north of France which has contaminatedthenearbyagriculturalsoils). Agriculturalpractices Mineralfertilizers Pesticides Organicamendments Atmosphericfallout SOIL=Accumulater INITIALSTOCK=geochemical backgroundlevel Parentmaterial Miningandmetallurgy Industrialandurbanactivities Figure1.1:Majorinputfluxesoftracemetalsintoagriculturalsoils. 18
Percentage 100 90 80 70 60 50 40 30 20 10 0 5 5 11 14 1 7 1 33 5 2 25 53 20 74 2 2 54 44 34 4 3 0 1 0 Cu Zn Pb Cd 4869to year 1 15190to year 1 696to year 1 54to year 1 AtmosphericFallout SludgeandCompost CalcicandMagnesiumAmendments AnimalWaste MineralFertilizers Plantprotectiveproducts Figure1.2:EstimationofannualinputoftracemetalsintoagriculturalsoilsofFrancewith theirprinciplesources.(valuestakenfromsorgreahademe,2007) Inthisthesiswork,wewillbeinterestedmoreparticularlyinCu,Zn,PbandCd,which arethemajortracemetalsfoundintheagriculturalsoils(ramade,2007;zheljazkovetal., 2008).CuandZnareessentialtraceelementsandarenecessaryfortheenzymaticreactio ofthebiologicalfunctioofthelivingorganisms(tyler,1981).contrary,theybecometoxic forsoilorganismsatexcessiveconcentratio.agriculturalandurbanwastesandplant protectiveproductsarethemajorsourcesofsoilcontaminationbytheseessentialelements. InFranceCuhasbeenusedintheproductsappliedtovineyardssinceseveraldecadesto fightagaittheparasitesorthe mildew.thusthevineyardssoils,nearlyamillionhectare infrance,havehighcupercentages(beyond500mg/kgofsoil),limitingincertaincasesthe microbialactivityandthendecreasingthefertilityofthesoilforanyothercrops. PbandCddonothaveaknownbiologicalrole(Maestrietal.,2010).Coideredas harmful,theycausenoxiousbiologicaleffectsevenatweakconcentratio(tyler,1981).pb contaminationofthesoilsismainlycausedbyatmosphericfalloutduetocombustio.the mineralfertilizers,especiallyphosphorusfertilizers,containcoiderablecontentsofmetals. BesidesthesearemajorinputsforCd(NziguhebaandSmolders,2008). 1.2. Factorsaffectingfateoftracemetalsinthesoils Itshouldbestressedthatthedynamicsofthetracemetalsintheenvironment dependontheirspeciation(theirchemicalforminthesoil)andontheintriicphysico chemicalcharacteristicsofthesoils.thesoilorganicmatterisknownforitsreactivitywith respecttometalssuchascuandpb.thetracemetalslikeznareadsorbedtoclayortoiron 19
hydroxidesinthesoils(tyler,1981;labanowskietal.,2008).duetotheretentionofmetals in the surface horizo of soils the quantities of metals traferred vertically towards undergroundwaterarelowinthemajorityofsoils(chassinetal.,1996). Thespeciationoftracemetal,theirmobilityandbioavailabilityarethecharacteristics linked to each other and are defined by the interaction of trace metals with their environmenti.e.thesoil,climateandbiotopeetc. Various physicochemical parameters of the soil influence the mobility and the bioavailabilityofthetracemetalsioils.amongwhichareph,redoxpotential,natureof thecomponentsofsoil,cationexchangecapacity,porosityofthesoilmatrix,available phosphatecontents,soilorganicmattercontentsandsoilbiologicalactivities(juste,1988; Alloway,1995).Theavailabilityofsoiltracemetalsdependsasawholeontheseparameters andnotonlyonasinglemechanism.theageandthenatureofthecontamination,thesoil moistureortheinteractiobetweendifferentmajorelementsinthesoilsandtracemetals canalsoinfluencethetracemetalmobilityandbioavailability. 1.2.a. phandredoxpotential Soil ph and redox potential directly influence all chemical processes and coequentlyalsodeterminethebehaviorofmetalsioils.manyauthorsunderlinethe majorinfluenceofphonthedynamicsoftracemetalsioils(alloway,1995;rieuwertset al.,2006).increaseinphincreasesthenumberofsorptioitesofclays,ofhydroxidesorof organicmatter(ureanddavidson,2002).thiscanincreasethequantityoftracemetal adsorbed to the soil components, provided that these components have an important affinityforagivenmetalandthatquantityofsorptioitesissufficient(ureanddavidson, 2002).Oppositetothis,itwasshownthatthesolubilityofmetalcatioincreaseswiththe reductioninph(pueyoetal.,2004),whileaniobecomelesssoluble(hesterberg,1998). Theredoxpotential(Eh)makesitpossibletocharacterizetheexchangesofelectro betweenthechemicalspecies.thuslowvaluesofehsupportthedissolutionofhydroxides andinvolveanincreaseintheconcentrationofmetalsassociatedwithsoilcomponents (Chaignon,2001).Moreover,modificationoftheoxidatiotateoftheligandsorelements withwhichthemetalsareboundioilinfluencesthesolubilityoftracemetalsindirectly. Forexample,inreducingconditio,sulphatesarereducedtosulphideswhichreadilytrap 20
the metalelements such as Pb, Cd, Zn (DeneuxMustin et al., 2003). The influence of oxydoreductionconditioofthesoilseemsveryimportantforthemobilityofthemetal elements,butitissecondarycomparedtothesoilph.foragiveoil,thevariationinehis oppositetothechangeinph,itincreaseswhenthephdecreases(deneuxmustinetal., 2003). 1.2.b. Inorganicsoilcotituents Inorganic soil cotituents like clay minerals, oxy (hydroxides), carbonates and phosphates,becauseoftheirchemicalproperties,playanimportantroleinthebehaviorof tracemetalsinthesoils. LiandLi,(2000)showedthattracemetalscanbeadsorbedandimmobilizedbyclay mineralsoralsobecomplexedtosoilorganicmatterbyformingorganometalliccomplex. Metalscanadsorbbetweenthelayersoronthesurfaceoftheclay(permanentcharge),on theedgesofthehydroxylgroups(variablecharge)andonthebridgesformedbecauseofthe irregularityofthematrixstructure(carrillogonzálezetal.,2006;sajiduetal.,2008).the sorptionforceofcatioonclaymineralsvarieswiththetypeofclay(carrillogonzálezet al.,2006).thus,claysmadeupoftwotetrahedrallayersandoneoctahedrallayer(e.gthe montmorillonite)haveahighercationexchangecapacity,andthusabettercapacityoffixing catio,thantheclaysmadeupofonetetrahedrallayerandoneoctahedrallayer(mcbride, 1994;Dubeetal.,2001;Brigattietal.,2005). Thepresenceofdifferenttypesofoxidesandoxyhydroxidesinthesoilscanalterthe tracemetalavailabilityinthesoilsbecauseofthedegreeaffinityofthemetalstothem.fe oxides (hematite, maghemite, magnetite) and oxyhydroxides (goethite, ferrihydrite, feroxyhite,akaganeite,lepidocrocite),aioxides(corundum),hydroxides(gibbsite)andoxy hydroxides(boehmite),aswellasmnoxides(birnessite)arecommonandnaturallypresent ioils(sparks,2003).theseoxidesareveryreactiveforthetracemetalsandareabletofix themtodifferingdegree.trivediandaxe(2001)classifiedoxidesaccordingtotheircapacity ofadsorption:mnoxides>feoxides>aioxides.thecoprecipitationoftracemetalswith oxidesreducestheirsolubilityandtheiravailability.thiscapacitywasusedintheworksof remediationofstronglycontaminatedsoils,inparticularbytheadditionofshotsoffe (Boissonetal.,1998;Menchetal.,2000).Thisproduct,composedmainlyofFe(97%FeO), 21