乌江水库水体中有机胶粒的三维荧光特征研究

超滤与三维荧光光谱的结合可以表征不同类型荧光物质相对分子量的分布规律,揭示它们的来源以及组分差异.本项研究用截留相对分子量为1 000和10 000的再生纤维素超滤膜,对乌江水库不同深度水体中的溶解有机质进行了分离,利用三维荧光光谱表征了3种不同相对分子量组分中发荧光有机质的光谱特征.结果表明:荧光物质主要存在于真溶液(＜1 000)中.水体在丰水期和枯水期的荧光峰存在差异.丰水期主要存在4种类型的荧光峰:类富里酸荧光A峰和C峰,类蛋白荧光峰B峰和D峰.枯水期则只表现出3种类型的荧光峰,类富里酸荧光峰C不明显,原因可能是此时水库处于蓄水状态,内部生物活动作用显著,产生的类蛋白荧光物质强度较大从而掩盖峰C的强度.然而72 m以下由于厌氧还原条件的出现,沉积物向水体释放了溶解有机质组分,原本强度被掩盖的荧光峰C明显出现在1 000～10 000组分中.

Research on the Characterization of Three Dimensional Excitation-emission Matrix of Dissolved Organic Colloids in Wujiang Reservoir

The combination of ultrafiltration, three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy was used to characterize the molecular weight distribution properties of different fluorescence materials, further revealing the differences in the sources and components. Dissolved organic matter (DOM) from different depth of Wujiang Reservoir fractionated by ultrafiltration with a nominal 1 000 and 10 000 molecular weight cut off regenerated cellulose membrane, then 3DEEM spectrophotometry was applied to investigate the characteristics of high molecular weight colloids (>10 000), middle molecular weight colloids(1 000-10 000) and true dissolved solutions(<1 000). The result indicated that fluorescence substances mostly existed in true dissolved solution. The types of fluorescence peak were different in wet season and dry season. There were four fluorescence peaks in wet season:the fulvic acid-like peak A and C, the protein-like peak B and D. The fulvic acid-like peak C disappeared in dry season, because the intensity of protein-like peaks were too strong to cover the intensity of peak C. In dry season, the reservoir retained water and the process of microorganism got more and more active, it produced newly protein-like substances. With the anaerobic-reductive surroundings established below the depth of 72 m, some dissolved organic matter released from the sediment again, which resulted in the intensity of fulvic acid-like peak C enhanced, it appeared in the middle molecular weight colloids.