海草生态系中DOM的三维荧光光谱特征

利用荧光激发-发射矩阵光谱(EEMs)技术研究了海南省陵水县新村湾海草生态系中溶解有机物(DOM)的三维荧光光谱特征。EEMs谱图表明，海草生态系中的DOM存在3个类腐殖质荧光A(230/430 nm)，C(350/440 nm)，M(300/380～400 nm)和2个类蛋白质荧光R(230/355～375 nm)，N(280～300/365～380 nm)。各荧光信号平均荧光强度的变化规律为R(0.304 RU)>A(0.194 RU)>M(0.147 RU)>N(0.125 RU)>C(0.051 RU)。类腐殖质荧光和类蛋白质荧光均表现为离岸近含量高;2个明显的低值区，分别出现在该湾海草茂密的西南部和东南部。各荧光信号在该湾的分布特征表明，控制类腐殖质荧光和类蛋白质荧光的动力学因素相同。荧光N与M和R之间以及荧光C与A之间具有较好的正相关关系，表明这些荧光具有相同的来源属性及地化行为。较高的荧光指数FI(均值为1.81)、较高的自生源指标BIX(均值为1.44)和较低的腐殖化指标HIX(HIXa和HIXb的均值分别为4.2和0.81)均表明海草生态系中DOM的强自生来源贡献和弱腐殖化程度。研究结果表明，海草生态系中DOM具有非常独特的荧光特征，不同于其他水生生态系。

The Fluorescence Characteristics of Dissolved Organic Matter (DOM) in the Seagrass Ecosystem from Hainan by Fluorescence Excitation-Emission Matrix Spectroscopy

The fluorescence characteristics of dissolved organic matter (DOM) were determined in the seagrass ecosystem collected in Xincun Bay of Hainan Island in late January, 2013, using fluorescence excitation-emission matrix spectroscopy (EEMs). EEMs spectra showed 2 types of fluorescence signals in DOM samples, three humic-like fluorescence peaks and two protein-like fluorescence peaks, respectively. The former included UVC peak A (Ex/Em: 230/430 nm), UVA peak C (Ex/Em: 350/440 nm), and UVA peak M (Ex/Em: 300/380～400 nm), while the latter included tryptophan-like peaks R (Ex/Em: 230/355～375 nm) and N (Ex/Em: 280～300/365～380 nm). Peak N was more like a combination of Peak M and Peak R. Moreover, free tyrosine-like molecules in DOM from the seagrass-beds ecosystem did not exist because the tyrosine-like fluorescence was not found. There were significant positive correlations of peak N with M and R (0.97 and 0.54 for R2, respectively), and peak A with C (0.86 for R2), showing their same sources and biogeochemical behaviors. The change law of mean fluorescence intensities of those fluorescence signals was R (0.304 RU) >A (0.194 RU) >M (0.147 RU) >N (0.125 RU) >C (0.051 RU). And, higher·L-1 concentrations of all the fluorescence occurred in the coastal waters inshore, with low values in two small regions located in the southwest and southeast of the bay where the seagrasses flourished. The distributions of those fluorescence signals in Xincun Bay suggested that the dynamics responsible for the humic-like fluorescence might be the same as that responsible for the protein-like fluorescence. The high fluorescence index (FI: 1.81), high biological index (BIX: 1.44) and low humification index (HIXa: 4.2 and HIXb: 0.81) showed that the DOM from the seagrass-dominant ecosystem has a strong autochthonous contribution and poor humification degree. The results clearly suggested that the DOM in this region has a rather unique fluorescence characteristic and is quite different from other aquatic environments.