沉积物中溶解性有机质的垂直分布光谱特性

Spectral characteristics of vertical distribution of dissolved organic matters in sediments

采用紫外光谱和三维荧光光谱结合平行因子分析(PARAFAC)方法对瀛湖沉积物中溶解有机质(dissolved organic matters,DOM)垂直分布的光谱特性进行了分析,利用荧光指数(fluorescence index,FI)、腐殖化指数(humification index,HIX)和生物源指数(biological index,BIX)解析了沉积物中DOM荧光组分、空间分布特征和来源。紫外光谱结果表明:瀛湖沉积物的UV254值在0.14~0.30之间,最大值出现在深度10~11 cm处,深层(20 cm以下深度)沉积物UV254值趋于稳定。A250/A365比值在3.69~9.98之间,均值为5.36,表明瀛湖沉积物DOM以富里酸为主。三维荧光光谱结合平行因子分析结果表明:沉积物DOM包含3类4个荧光组分,即类腐殖质组分(C1和C2)、类蛋白组分(C3和C4),其中,类腐殖质组分的荧光强度约占全部组分荧光强度的60.7%;随着深度的增加,3个采样点的类蛋白质组分(C3和C4)的荧光强度均呈现下降趋势。FI、HIX和BIX都表明瀛湖沉积物DOM的来源主要是由沉积物中自生微生物活动产生。其中,FI在1.73~2.10范围内,BIX处于0.72~0.96范围内,HIX在1.39~4.72范围内。

UV spectroscopy and three-dimensional excitation-emission matrix （EEM） fluorescence spectroscopy combined with parallel factor analysis （PARAFAC） were used for the analysis of vertical distribution character- ization of dissolved organic matter （DOM） in the sediments from Lake Yinghu. Fluorescence index （FI）, bio- logical index （BIX） , and humification index （HIX） were applied to investigate the fluorescent components and characteristics of DOM, and its source. The UV spectroscopy results showed that UV254 values varied from 0. 14 to 0.30, with the maximum value appearing at the depth of 10 to 11 cm, and the stable values maintained under 20 cm depth. A25o/A365 values varied from 3.69 to 9.98, with an average of 5.36, indicating that fulvic acid was the major component of DOM. The EEM-PARAFAC results identified four fluorescent components, including hu- mie acid （HA） -like materials （ C1 and C2）, tryptophan-like materials （ C3 ）, and tyrosine-like materials （C4）. The fluorescent intensity of HA-like materials accounted for 60.7% of all fluorescent intensities. The fluorescent intensities of protein-like materials （C3 and C4） decreased in the vertical profile. FI, BIX, and HIX indicated that DOM was mainly resulted from autochthonous microbial activities in sediment. FI, BIX, and HIX values ranged from 1.73 to 2. 10, O. 72 to 0.96, 1.39 to 4.72, respectively.