Influence of water chemistry and dissolved organic matter (DOM) molecular size on copper and mercury binding determined by multiresponse fluorescence quenching

► PARAFAC analysis of the quenching of EEM of dissolved organic matter by Cu and Hg. ► Multiresponse model should be chosen to calculate the binding parameters. ► HMW DOM has stronger binding affinity to Cu2+ and Hg2+ than bulk and LMW DOM. ► DOM composition and size are important factors regulating metal complexation in freshwater.