溶解有机质的三维荧光光谱特征研究

Three-Dimensional Excitation Emission Matrix Fluorescence Spectroscopic Characterization of Dissolved Organic Matter

利用三维荧光光谱研究了河流、湖泊等不同来源溶解有机质(DOM)的荧光光谱特性。河流DOM的 三维荧光光谱图中含有类富里酸荧光峰A和C以及类蛋白荧光峰B和D,一般而言,类富里酸荧光峰强度 比较大,或者只有类富里酸荧光,但是受人类活动污染河流DOM的三维荧光光谱图中具有极强的类蛋白荧 光。同样,红枫湖DOM可以由陆源输入,还可以由水体内微生物活动产生,具有4个荧光峰,受人类活动 影响比较显著的百花湖DOM则表现出强的类蛋白荧光。贵阳市地下水中EOM含量相对较低,一般只含有 类富里酸荧光峰,但是若受生产生活污水污染,也可检测出强的类蛋白荧光峰。考察DOM含量(以DOC表 示)与类富里酸荧光强度(peak C)以及在254 nm处紫外吸收光谱强度的关系时发现它们都具有良好的线性 相关关系(r2=0.82和0．95),而紫外区类富里酸荧光与可见区类富里酸荧光之间也存在良好的线性相关关 系(r2=0.96)。此外,pH对DOM的三维荧光光谱具有显著影响,并且类富里酸荧光峰A和C的pH值效应 基本一致,荧光强度最大值出现在pH 10左右,类蛋白荧光峰B的pH值效应与之略有区别,荧光强度最大 值出现pH 8．5左右。

Three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM） was applied to characterize the fluorescence properties of dissolved organic matter （DOM） in lakes, rivers, streams, and ground waters. The results showed that the 3DEEM of DOM in aquatic environments mainly have four fluorescence peaks： peak A and C was referred to as fulvic-like fluorescence, and peak B and D was referred to as protein-like fluorescence. Results of river water DOM typically showed strong fulvic-like fluorescence. Polluted river waters often showed strong protein-like fluorescence. Four peaks were also found in the 3DEEM of lake DOM, which can origin from terrestrial runoff or from sources within the lakes. In Lake Baihua, strong protein-like fluorescence was found owing to the pollution by municipal wastewaters. Groundwater DOM has. relatively lower DOC concentrations at 0.56-0.85 mg·L^-1 and is characterized by fulvic-like fluorescence only if it was polluted by municipal wastewaters, and then it has strong protein-like fluorescence. The authors demonstrate that for all DOM samples, fluorescence intensity at peak C and absorption at 254 nm both showed a strong correlation with DOC concentrations（ r^2 = 0.82 and 0.95, respectively）. Also a strong linear correlation between UV- fulvic-like fluorescence and visible fulvic-like fluorescence was found （ r^2 = 0.96）. The fulvic-like fluorescence at peak A and C varied in accordance to each other with the pH of the DOM samples, and the maximum fluorescence occurred at pH 10, while the maximum value of protein-like fluorescence （peak B） occurred at pH around 8.5.