基于UV-vis及EEMs解析周村水库夏秋季降雨不同相对分子质量DOM的光谱特征及来源

Spectral Characteristics and Sources of Dissolved Organic Matter With Different Relative Molecular Weight from Rainwater From Summer and Autumn in the Zhoucun Reservoir Based on UV-Vis and EEMs

运用三维荧光光谱(EEMs)技术结合平行因子分析法(PARAFAC)以及紫外-可见光谱技术,对周村水库夏秋季降雨不同相对分子质量雨水的溶解性有机物(DOM)光谱特征和来源进行分析.结果表明,夏秋季降雨不同相对分子质量DOM的紫外-可见吸收光谱并无明显特征峰,吸收系数的变异系数在75%~469%之间,表明其性质在不同季节和相对分子质量上存在差异;a254和E3/E4变化说明DOM的相对浓度和富里酸所占DOM的比例随着季节由夏入秋而增加;三维荧光通过PARAFAC解析出4种组分,分别为类腐殖质(C1、C2)、可见区富里酸(C3)和类蛋白(C4);对4个组分进行相关性分析,结果显示C1与C2、C3以及C4具有显著的相关性(P<0.01),C2与C3具有显著的相关性(P<0.01);夏秋季降雨DOM总荧光强度以及各组分荧光强度差异明显(P<0.05),类腐殖质(C1+C2)是其主要成分、富里酸的荧光强度和所占比例随着季节由夏入秋而增加、类蛋白随着季节由夏入秋而减少;夏秋季降雨有机物来源都呈现以自生源为主的特征,夏季降雨具有自生源特征更强、类蛋白物质含量和占比更多的特点;PCA分析显示夏秋季降雨中不同相对分子质量雨水荧光特征差异明显,并且组分C1、C2和C3与DOM特征参数[HIX、Fn(355)、Fn(280)、E3/E4、a254]以及水质参数(硝氮、氨氮、总氮以及有机碳)显著相关性(P<0.01).通过对夏秋季不同降雨相对分子质量的DOM光谱特征研究,可以进一步分析水库大气沉降型外源输入的有机物污染特征,并为水库水质管理提供技术支持.

Based on excitation emission matrix spectroscopy (EEMs) technology combined with parallel factor analysis (PARAFAC) and UV-Vis spectra, we analyzed the spectral characteristics and sources of dissolved organic matter (DOM) in rainwater with different DOC molecular weight in summer and autumn in the Zhoucun Reservoir. The results show that the UV-Vis absorption spectrum of DOM have no notably characteristic peak and the variation coefficient of the absorption coefficient ranges between 75% and 469%, which shows the properties of DOM with different molecular weight. The changes of a254 and E3/E4 show that the relative concentration of DOM and the proportion of fulvic acid in DOM both increase from summer to autumn, respectively;Two humic-like substances (C1, C2), one fulvic-like substance (C3), and one protein-like substance (C4) were identified with the PARAFAC model, with a significant correlation coefficient (P<0.01) in C1&C2/C3/C4 and C2&C3, respectively. The total DOM fluorescence intensity and the fluorescence intensity of each component exhibit significantly different distributions (P<0.01). Moreover, C1+C2 account for the majority proportion of DOM and C3 and C4 exhibit an increase and decrease from summer to autumn, respectively. The rainwater in summer and autumn both exhibita strong autochthonous component characteristics and the summer rainwater has higher autochthonous characteristics. The PCA shows that the spectral characteristics of the rainwater exhibit notable differences. Moreover, C1, C2, and C3 exhibit a significant correlation coefficient (P<0.01) with DOM indices[HIX, Fn(355), Fn(280), E3/E4, a254] and water quality parameters. The results contribute to the future exploration and control of organic carbon pollution sources by managers of the Zhoucun Reservoir.