FinalReporttoCityofSt.ClairShoresPCBContaminantProfileinaSedimentCorefromtheLangeandRevereCanalsSt.ClairShoresMay20,2003LindaSchweitzer,Ph.D.MarkBaskaran,Ph.D.OaklandUniversityDepartmentofGeologyDepartmentofChemistryWayneStateUniversityRochester,MI48309Detroit,MI48202ExecutiveSummaryInanefforttoestablishadepositiontimeframeforthePCBscontaminatingtheLangeandReverecanalsinSt.ClairShores,MacombCounty,throughtheCityofSt.ClairShores,fundedthisprojecttoinvestigatethePCBdumping.Therefore,thisstudyseekstoestablishthroughon-sitesedimentcoresamplingandsubsequentlaboratoryanalyses,atimetableforthePCBcontaminationoftheLangeandReverecanals.Additionally,whilenotpartoftheprojectcontract,characterizingthechemicalnatureofthePCBsmakesitpossibletosuggestapotentialcontaminationsource.Thesedataarenotrelevantforestablishinganexposureassessment,however,orforcorrelatingthePCBspresentinthecanalstohealtheffectsinpeopleoranimalsresidinginSt.ClairShores.ThisstudywasdesignedexclusivelyfordelineatingthetimecourseofthePCBcontamination,notfordetermininghealtheffects,andinfact,thetwocannotbecorrelated.TheMichiganDepartmentofCommunityHealthissuedahealthassessmentreportthatshouldbereferredtoforthatpurpose.Thereisevidenceofperiodicmixingwithinthesedimentsinthecanal,butadefiniteoverallpatternofsedimentlayeringwhichallowedustodetermineatimetableforthePCBcontamination.ThedatasuggestamajorPCBdumpingdatingtoabout1983plusorminusthreeyears.Aslightlylesserdischargedatingtothemid1960scorrespondstotheknownpeakuseofPCBs,priortotheregulatorybanintheearly1970s.Webelievethattherewasnotanotherreleaseafter1983,andthatthePCBswerestoredtosomedegreeinthedrainagesystem(associatedwithsediments),andperiodicallyreleasedintothecanalsovertime.DependingonthelakelevelsthatebbandflowbetweenLakeSt.ClairandthedrainagesystemthatfeedstheLangeandReverecanals,movementofthecontaminatedsedimentsfromthedrainagesystemintothecanalsvariedovertime.PCBsareubiquitousintheenvironment,soweexpecttofindPCBs