激光诱导水体中DOM的荧光猝灭特性分析

An Analysis of Quenching Characteristics of DOM in Water by Laser Induced Fluorescence

以355 nm激光为激发光源,在实验室中用激光诱导荧光(LIF)方法以不同浓度的腐殖酸为测量样品研究了水体中溶解有机物(DOM)的荧光猝灭特性。研究表明,随着腐殖酸浓度的增加,水拉曼散射强度逐渐减弱,当浓度为40 mg.L-1时,水拉曼散射信号几乎完全被DOM的荧光基态分子所吸收,而DOM的荧光强度随着浓度的增加,先是线性增加,当浓度为16 mg.L-1时,荧光强度达到最大,再继续增加腐殖酸浓度,荧光强度则缓慢降低。因此,通过对不同浓度下腐殖酸荧光猝灭特性的分析,可以更加有效的实现水体中DOM浓度的探测。

In the experiment an excitation resource at 355 nm from a third harmonic Q-switched Nd： YAG laser was used, and the commercial humie acid of different concentrations was used as the research samples. The fluorescence spectrum of dissolved organic matter （DOM） in combination with laser-induced fluorescence （LIF） measurements was measured in the laboratory, and the characteristics of fluorescence quenching of DOM were analyzed. The results show that the intensity of water Raman scattering and DOM fluorescence was reduced gradually and increased linearly respectively with raising the concentration of humie acid. The water Raman scattering signal was absorbed almost completely by the ground state molecules of DOM at 40 mg·L^-1 , and the fluorescence intensity of DOM reached a maximum at 16 mg·L^-1 and decreased slowly with further increasing the concentration of humie acid. Consequently, we can achieve better monitoring of DOM in water through analyzing the characteristics of fluorescence quenching at different concentrations of humie acid.