[Three-dimensional excitation emission matrix fluorescence spectroscopic characterization of the complexation between mercury (II) and dissolved organic matter].

With the development of fluorescence technique, three-dimensional excitation emission matrix fluorescence spectroscopy (3DEEM) was widely applied to characterize the nature of dissolved organic matter (DOM) in natural waters since the last decade. 3DEEM and fluorescence quenching titration were used to study the interaction between Hg(II) and DOM. The results show that a general decrease in intensity for individual peak A, B and C was found as concentrations of Hg(II) increased. pH is the main parameter that strongly influences the Hg(II)-DOM complexation. The addition of Cl- ion to the Hg(II)-DOM system caused an increase in fluorescence intensity. The results also show that the addition of Ca(II) solution strongly enhanced the fluorescence intensity for humic-like fluorescence, while the protein-like fluorescence only slightly enhanced. On the contrary, no fluorescence enhancement was found in the Hg(II)-DOM system after the addition of Mg(II) ion. A decrease in fluorescence emission intensity was found after the addition of Cu(II) ion to the Hg(II)-DOM solution.