蠡湖表层沉积物荧光溶解性有机质(FDOM)荧光光谱特征

Fluorescence Spectral Characteristics of Fluorescent Dissolved Organic Matter(FDOM) in the Surface Sediments from Lihu Lake

应用三维荧光光谱技术(EEMS),研究了蠡湖表层沉积物荧光溶解性有机质(FDOM)光谱特征,并探讨了沉积物中FDOM来源及与有机氮(SON)、无机氮(SIN)之间的相关性.结果表明,蠡湖表层沉积物FDOM由2类3个荧光组分组成,即类腐殖质荧光组分C1(240,310/420 nm)、C2(260,360/460 nm)和类色氨酸荧光组分C3(225,275/340 nm).总荧光强度变化范围为:49.97~159.19 R.U.·g-1,在空间上呈自东向西依次递减,且沿岸区高于湖心区的趋势,C1、C2和C3相对比例分别为33.63%、26.87%、39.49%.荧光指数(FI)、生物源指数(BIX)和腐殖化指数(HIX)的变化范围分别为:1.96~2.22、0.69~0.94、2.62~4.39,显示蠡湖表层沉积物FDOM的来源具有自生源特性,主要为自生微生物、藻类等新近自生源.相关性分析表明,表层沉积物FDOM各组分与SON和SIN均呈显著正相关(P<0.01),且与SIN的相关性较高.

This study investigated the spectral characteristics of fluorescent dissolved organic matter（ FDOM） in sediments of Lihu Lake using three-dimensional excitation-emission matrix fluorescence spectroscopy（ EEMS）,and discussed the correlation between source of FDOM and organic or inorganic nitrogen. The results indicated that the surface sediments in Lihu Lake consisted of three fluorescence fractions（ Ⅱ）,humic-like C1（ 240,310/420 nm）,C2（ 260,360/460 nm）,and tryptophan-like C3（ 225,275/340 nm）.The total fluorescence intensity ranged from 49. 97 to 159. 19 R. U.·g-1,and decreased from east to west with higher values in coast district than in lake center. The relative proportions of C1,C2,and C3 were 33. 63%,26. 87% and 39. 49%,respectively. The fluorescence index（ FI）,biological origin index（ BIX）,and humification index（ HIX） ranged from 1. 96 to 2. 22,0. 69 to 0. 94,and2. 62 to 4. 39. It indicated that the main source of FDOM in Lihu Lake was from endogenesis,and mainly derived from microbes,algae and other newly autochthonous sources. The results illustrated,the fluorescence intensity had significant correlation with organic and inorganic nitrogen（ P〈0. 01）,and had higher correlation with inorganic nitrogen.