简介:Inordertobetterunderstandthecompositionalandstructuralcomplexityofdissolvedorganicmatter(DOM)macromoleculesandprovidemechanisticinformationonthebindingofhydrophobicorganiccontaminants(HOCs)toDOM,wefractionatedlargeamountsoflakewaterintothreehydrophobicDOM-fractions.Thevariationofthepartitioningcoef?cients(KDOC)ofpyreneatdifferentpHlevelswasexaminedby?orescencequenchingtitration.Resultsshowthat,relativetothemorepolaracidicDOM-fractions,thehydrophobicneutralfractionexhibitsahighersorptionabilitytopyrene.Generally,thesorptionofpyrenetothethreehydrophobicfractionsisstronglypH-dependent.TheKDOCvaluesofpyrenegenerallyincreasewithdecreasingpHlevels,whichisespeciallyobviousinthesorptionofpyrenetothefulvicacidfractions,suggestingthatthebindingiscontrolledbyhydrophobicinteractions.Themechanismsunderlyingthebindingofpyrenetothehydrophobicfractionswerealsodiscussed.Ourdataarebene?cialtofurtherunderstandingthebindingofHOCstoDOMandhowithasbeenaffected,whichmayresultinmoreaccuratepredictionsofKDOC.