运用紫外-可见吸收光谱和分子荧光光谱,对阿哈湖10个采样点沉积物孔隙水中溶解有机质(Dis-solved organic matter,DOM)的光谱特征进行了研究.结果表明,各水样的紫外-可见吸收光谱在300 nm与400nm处比值表明孔隙水中DOM腐殖化程度比较低、芳香性较小,分子量分布以小分子量的富里酸为主,大分子量的腐殖酸含量相对较少.根据样品有机质腐殖化和芳香性程度以及溶解有机碳(Dis-soned organic carbon,DOC)浓度,可知阿哈湖主要受到点源污染而非面源污染.10个水样的荧光光谱图显示阿哈湖沉积物孔隙水中DOM均出现三类明显的荧光峰,分别代表了类腐殖酸荧光、类富里酸荧光和类蛋白荧光.类腐殖酸和类富里酸的荧光强度变化趋势大体一致,说明这两类物质可能具有相似的来源.阿哈湖沉积物孔隙水中DOM的荧光比值(f450/f500)接近1.6,说明阿哈湖中的腐殖质主要来源于陆源污染物.%Ultraviolet-visible absorption spectrophotometer and fluorescence spectrophotometer were employed in this study to analyze spectral characteristics of dissolved organic matter (DOM) in sediment pore water at 10 sampling locations in Lake Aha, a man-made karstic plateau lake and a key drinking-water source for Guiyang City, Guizhou Province. The UV-Vis absorption ratio values (300 nm/400 nm) showed that the degree of humification and aromaticity of DOM in pore water were relatively low, and fnlvic acid with small molecular weights was the main component other than humic acid. In addition, the degree of hunfification and aromaticity demonstrated that Lake Aha was mainly polluted by point source pollution rather than non-point source pollution. This was further proved by comparing the concentrations of dissolved organic carbon (DOC) at different locations. Three obvious fluorescence peaks were observed in fluorescence spectra of DOM in sediment pore water at ten sampling locations of Lake Aha. These fluorescence peaks probably represented humic acid-like, fulvic acid-like and protein-like substance respectively. A high similarity in the change of fluorescence intensity for humic acid-like and fnlvic acidlike at the 10 sampling locations might indicate that these two substances were from the similar source. Fluorescence ratio values (f450/f500) of DOM in sediment pore water of Lake Aha were close to 1.6 and indicated that humic substances in Lake Aha mainly came from terrigenous pollutants.
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