Seasonal variations of ultraviolet-visible and excitation emission matrix spectroscopy characteristics of overlying water dissolved organic matter in Zhoucun Reservoir, Shandong Province

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（UV-vis），对周村水库季节演替过程中沉积物上覆水溶解性有机物（DOM）的紫外-可见以及三维荧光光谱特征进行分析.结果表明：周村水库上覆水的总氮、溶解性总氮、总有机碳和溶解性有机碳的季节性差异显著，并且冬季总氮浓度最高、夏秋季总有机碳浓度较高；夏秋季上覆水DOM的吸收系数a₂₅₄和a₃₅₅均高于冬春季，与有机物的分布相一致；4个季节上覆水DOM的E3/E4均大于3.5，说明DOM以富里酸为主，E2/E3（富里酸占DOM的比例）在夏秋季低于冬春季，而且各季节S_R均大于1，表明DOM主要为生物源；三维荧光通过PARAFAC解析出3种组分：类腐殖质（C1）、可见区富里酸（C2）和类蛋白（C3）；对3个组分进行相关性分析，结果显示C1、C2、C3之间具有显著的相关性；DOM的总荧光强度以及各组分的荧光强度均呈现出夏秋季高、冬春季低的特征，且各季节间差异显著；周村水库4个季节的DOM生物源指数（BIX）在0.8~1.0之间，表明水库DOM具有较强的自生源特征，与腐殖程度指标（HIX）的结果相吻合；主成分分析显示周村水库上覆水DOM的光谱特征差异明显，夏秋季的DOM光谱特征相近、冬春季的水体DOM特征相似；并且组分C1、C2、C3与DOM特征参数（a₂₅₄、SUVA₂₈₀、HIX、FI、BIX）以及溶解性有机碳呈显著相关.各荧光组分与水质参数（溶解性总氮和溶解性有机碳）的多元线性回归呈现很好的拟合，通过建立回归方程可以为以后研究周村水库水体四季的DOM光谱特征，分析水库水体的有机物污染特征，并为水库水质管理提供技术支持.;Based on excitation emission matrix spectroscopy (EEMs) technology combined with the parallel factor analysis (PARAFAC), and UV-vis spectra, we analyzed the impact of seasonal variations on distribution and spectral characteristics of dissolved organic matter (DOM) in Zhoucun Reservoir. Results showed that the concentration of nitrogen and organic matter exhibited significant seasonal differences, and the reservoir has more total nitrogen and less total organic carbon in winter. The a₂₅₄ and a₃₅₅ in summer and autumn were both higher than those in winter and spring, which was consistent with the changes of organic matter. The E3/E4>3.5 showed that the fulvic acid accounted for the majority proportion in DOM; the concentrations of fulvic acid in summer and autumn were higher than those in winter and spring based on E2/E3. Moreover, the S_R>1 indicated the DOM exhibited autochthonous characteristics. One humic-like substances (C1), one fulvic-like substances (C2) and one protein-like substance (C3) were identified by PARAFAC model, and there exhibited significantly correlation coefficient in C1 & C2 & C3; Total fluorescence intensity and the fluorescence intensity of each component exhibited high concentration for summer and autumn and low concentration for winter and spring distribution characteristics. Total fluorescence intensity and the fluorescence intensity of each component exhibited significant seasonal difference. The DOM exhibited strong autochthonous component characteristics based on BIX and HIX indexes; Principal component analysis showed that the spectral characteristics exhibited obvious difference in the whole year, and the DOM spectral characteristics of summer and autumn are similar, and the DOM characteristics of water in winter and spring are similar. Moreover, the C1, C2 and C3 exhibited significantly correlation coefficient with DOM indices (FI, β/α) and dissolved organic carbon. Those three components and water quality (dissolved total nitrogen and dissolved organic carbon) of overlying water could be connected with spectral characteristic by nonlinear multiple. From all the results, it could contribute to explore and control the organic carbon pollution sources for the managers of Zhoucun Reservoir in the future.