水溶性有机物电子转移能力与荧光峰强度的关系研究

以不同来源的水溶性有机物（DOM）为供试材料,采用电化学方法和荧光光谱法研究了DOM电子转移能力及其与荧光峰强度的关系.采用库仑安培法测定DOM电子转移能力,其中测得的电子接受能力为635.6～1 049.3μmol.（g.C）-1,电子供给能力为27.3～42.3μmol.（g.C）-1.利用循环伏安法研究DOM电化学活性,发现其氧化还原电位在-731～-996 mV（vs.Ag/AgCl）之间.经过电位跃阶法三次氧化还原循环后电子转移能力仍可维持在232.1～897.2μmol.（g.C）-1之间,电子循环率为36.7%～78.2%,说明DOM具有重复利用、反复转移电子的特性.采用荧光激发发射光谱法（EEMS）测定DOM的类富里酸荧光峰强度并比较其与DOM电子转移能力的关系,发现DOM的类富里酸荧光峰强度与DOM的电子循环率具有显著相关（r2=0.92）.实验结果为理解DOM在元素循环、污染物降解以及生物地球化学循环中的作用提供科学依据.

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.