鄱阳湖CDOM三维荧光光谱的平行因子分析

Fluorescent characteristics of CDOM in Poyang Lake analyzed by three-dimensional excitation-emission matrix spectroscopy and parallel factor analysis

利用三维荧光光谱(3DEEM)结合平行因子分析法(PARAFAC),对鄱阳湖水样的荧光光谱进行研究,探讨了有色溶解有机物(CDOM)荧光组分与氮磷营养盐之间的关系.结果表明,鄱阳湖水体CDOM由2类3个荧光组分组成,即类腐殖荧光组分C1(245/391nm)和C2(255,340/453nm),及类酪氨酸组分C3(275/304nm).在CDOM组成中,微生物作用类腐殖质C1占40.8%,陆源类腐殖质C2占30.8%,类酪氨酸物质占28.4%.类腐殖质和类酪氨酸在两个极端水文条件下表现出截然不同规律,即类腐殖质在枯水期荧光强度和贡献都为最低,在丰水期贡献率最大,而类酪氨酸在丰水期,荧光强度和贡献为最低,在枯水期贡献率最大.CDOM各荧光组分强度分布因水文条件不同具有差异性.各荧光组分在同一水文条件下,荧光强度变化趋势相似.荧光光谱参数结果表明,鄱阳湖水中CDOM呈现外源和内源的特征,其中枯水期以外源输入为主.各荧光组分都与水体中总氮(TN)和溶解性总氮(DTN)呈现显著正相关,类酪氨酸组分与总磷(TP)呈现显著正相关.

Based on the three-dimensional excitation-emission matrix spectrum （3DEEM） and the parallel factor analysis （PARAFAC） of Poyang Lake samples, a relationship between fluorescent components of chromophoric dissolved organic matter （CDOM） and nitrogen and phosphorus nutrients in the lake was established. Three fluorescence components were identified for CDOM including humic-like components C1 （245/391nm）; C2 （255, 340/453nm）, each of which accounted for 40.8% and 30.8% of total CDOM, and a tyrosine-like component C3 （275/304nm） with a contribution of 28.4% to total CDOM. The fluorescent intensities and proportion of humic-like components were the lowest in the dry season but the highest in the flooding season. On the contrary, the tyrosine-like component was the lowest contributor to total CDOM in the flooding season but the highest in the dry season. The fluorescent intensity of each component was subject to the changes in lacustral hydrological conditions. Similar fluorescent intensity of different components was observed under the same hydrological condition. The CDOM in Poyang Lake originated from both allochthonous and autochthonous sources, yet the allochthonous source dominated in the dry season. In addition, the fluorescent intensities of all components showed significantly positive correlations with total nitrogen （TN） and dissolved total nitrogen （DTN）, and tyrosine-like component was significantly and positively correlated with total phosphorus （TP）.