Spectral characteristics of dissolved organic matter in the surface sediments from a canyon-shaped, stratified, water-source reservoir

Abstract

结合三维荧光光谱技术（EEMs）与紫外吸收光谱（UV-vis），并利用平行因子分析（PARAFAC）的方法，对金盆水库表层沉积物中溶解性有机质（DOM）光谱的空间分布特征及来源进行分析，并探讨沉积物DOM的荧光组分与可溶性有机氮（SON）、可溶性无机氮（SIN）之间的相关性.结果表明，金盆水库表层沉积物DOM由3类荧光组分组成，分别是类富里酸C1（235 nm，315 nm/430 nm）、类色氨酸C2（220 nm，275 nm/330 nm）和类胡敏酸C3（265 nm/520 nm），各组分荧光强度占总荧光强度百分比的平均值分别为43.15%、31.54%和25.31%.表层沉积物DOM浓度在空间上呈现从上游到主库区先减少后增加的趋势.光谱斜率S_275-295、S_350-400和光谱斜率比S_R反映出各采样点陆源与内源占比的差异性.荧光指数、自生源指标和腐殖化指标都表明金盆水库沉积物DOM的来源具有内源与陆源双重特征.相关性分析表明，表层沉积物DOM各组分与SON和SIN均呈显著正相关，说明DOM与氮元素的迁移转化密切相关.;The distribution characteristics and sources of dissolved organic matter (DOM) in surface sediments of Jinpen Reservoir were investigated using fluorescence ultraviolet-visible (UV-vis) and excitation-emission matrix spectra combined with parallel analysis (EEMs-PARAFAC). The correlation between source of DOM and soluble organic or soluble inorganic nitrogen was explored. The results showed that three fluorescent components were identified by PARAFAC model in surface sediments of Jinpen Reservoir, including fulvic-like component (C1:235 nm, 315 nm/430 nm), protein-like (C2:220 nm, 275 nm/330 nm) and humic-like (C3:265 nm/520 nm). The relative proportions of C1, C2 and C3 were 43.15%, 31.54% and 25.31%, respectively. DOM showed spatial distribution characteristics, which first decreased then increased from upstream to the reservoir area. The spectral slop (S_275-295, S_350-400) and the spectral slope ratio (S_R) could be used to distinguish the difference in endogenesis and terrigenous component from different sampling sites. Based on the fluorescence index, biological index and humification index, the DOM of sediments exhibited both endogenous and terrigenous contribution in Jinpen Reservoir. Meanwhile, the fluorescence intensity had significantly correlation with soluble organic and soluble inorganic nitrogen, and DOM was closely related to the migration and transformation of nitrogen in sediments.