[Relationship between electron transfer capacity and fluorescence characteristics of dissolved organic matter]

This study demonstrated the relationship between redox activity and fluorescence characteristics of different dissolved organic matter (DOM) employing a combined method of electrochemistry and fluorescence spectroscopy. Chronoamperometry was used to quantitatively evaluate the electron transfer capacity (ETC) of DOM. Data showed that the electron accepting capacity of DOM ranged from 635.6 micromol x (g x C)(-1) to 1049.3 micromol x (g x C)(-1), and the electron donating capacity ranged from 27.3 micromol x (g x C)(-1) to 42.3 micromol x (g x C)(-1). For all DOM tested, the cyclic voltammetries (CVs) showed an evident pair of redox peak with the redox potentials in the range from -731 mV to -996 mV (vs. Ag/AgCl), suggesting their electrochemical activity. Using the multi-potential steps method, the ETC was measured to be 232.1-897.2 micromol x (g x C)(-1) and the electron recycling rates (ERRs) were 36.7%-78.2%, indicating the electron transfer of DOM has a reversible character. Using fluorescence excitation-emission spectroscopy (EEMs), the ERRs were found to be highly correlated with the fulvic-like fluorescence intensity of DOM with a correlation coefficient of 0. 92. This study can potentially provide a scientific base for understanding the roles of DOM in the elements cycles, pollutants degradation and biogeochemical cycles.