中文摘要：

不同pH条件下（pH=2、4、6、8、10、12）培养洱海沉积物,利用三维荧光光谱（3DEEM）技术研究了其溶解性有机质（DOM）在培养前后荧光光谱特征变化.结果表明：①培养前,洱海沉积物DOM类富里酸荧光峰在pH（2—8）发生＂红移＂,pH（8—12）时发生＂蓝移＂,紫外区类富里酸（A峰）荧光强度〉可见区类富里酸（C峰）荧光强度,类富里酸荧光物质受pH影响不大,这与其结构复杂且不易降解有关.②培养前,洱海沉积物DOM类酪氨酸物质受pH影响较大,可见光区类酪氨酸（B1峰）荧光强度〉紫外区类酪氨酸（B2峰）荧光强度,这与其结构不稳定、易降解及其酚羟基解离pH范围有关.③培养后,洱海沉积物DOM可见区与紫外区类富里酸荧光强度比培养前分别降低了34.1%、32.2%,可见区与紫外区类酪氨酸荧光强度较培养前升高了57.06%、86.65%,即洱海沉积物DOM在培养后部分类富里酸物质逐渐降解为易被微生物利用的类酪氨酸物质,且在偏碱性（pH=8）环境条件下转化最为明显,沉积物DOM组成结构的转化对湖泊水污染与富营养化具有重要指示意义.

英文摘要：

The sediments of Erhai Lake were cultivated under different pH conditions （pH = 2,4,6, 8,10,12 ） , and three-dimensional excitation-emission matrix fluorescence spectra （ 3DEEM ） was used to evaluate the change of fluorescence characteristics of dissolved organic matter （DOM） during the process of cultivation. First, ＂ red shift＂ and ＂ blue shift＂ occurred for the fulvic-like fluorescence peak positions of the DOM before cultivation under pH （2--8） and pH （8--12）, respectively. The fluorescence intensity of fulvic-like ultraviolet region （peak A） was higher than that of fulvic-like visible region （peak C ） , and the pH had no effect on fulvie-like fluorescence materials because of its complicated structure and resistance to degradation. Second, pH had some significant effect on tyrosine class materials of the DOM before cultivation. The fluorescence intensity follows the order of： tyrosine-like visible region （ peak B1 ） 〉 tyrosine-like ultraviolet region （ peak B2 ） , because of its unstable structure, ease of degradation and phenolic hydroxyl dissociation.Third, the fluorescence intensity of visible and ultraviolet region of the fulvic-like reduced to 34.1% and 32.22% after cultivation, respectively ; the fluorescence intensity of visible and ultraviolet region tyrosine-like increased by 57.06% and 86.65% after cultivation, respectively. DOM biological transformation was promoted during the cultivation of the sediments, some fulvic-like materials transformed into tyrosine class substances by microorganisms, and the transformation was the fastest in the slightly alkaline （ pH = 8 ） conditions.