In this study,synchronous fluorescence spectroscopy and Fourier transform infrared spectroscopy combined with two-dimensional correlation spectroscopy analyses were applied to investigate binding characteristics between dissolved organic matter(DOM)and multiple Cu2+and Cd2+through quenching titration experiments.The results suggested that the binding constant(lgKM)for Cu2+and Cd2+ranged from 4.75～5.18 and 3.71～4.12,respectively,indicating the stronger binding affinity with Cu2+than Cd2+.The binding sequence to DOM for Cu2+both were 430 nm～500 nm＞330 nm～420 nm under 0 and 100 μmol/L Cd2+,and the lgKM for Cu2+ranged from 4.56～4.95 in the presence of Cd2+.The comparative result showed that the presence of Cd2+had no effect on the binding sequence,but attenuate the binding affinity between DOM and Cu2+.FTIR results showed that,the structural changes of DOM upon interaction with Cu2+under 0 and 100 μmol/L Cd2+followed the order of phenolic C—O＞amide N—H＞amide C=O＞carboxyl C=O＞aromatic C—H＞polysaccharides C—O and amide N—H＞amide C=O＞phenolic C—O＞aromatic C—H＞polysaccharides C—O,respectively.The phenolic C—O interacted with Cd2+and then affect the interaction between Cu2+and DOM functional groups,such as phenolic C—O and carboxyl C=O.The bioavailability and ecological risk of heavy metals should be pay close attention under co-existence of heavy metals in wa-ter environments.
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