兴凯湖沉积物富里酸荧光特性研究

采集黑龙江省兴凯湖4个点位沉积物样品(样品号HXXD，HXXX，HXDX，HXDB)，开展了沉积物富里酸(fulvic acid, FA)荧光特性研究。二维荧光光谱、三维荧光光谱均显示HXXD点位FA的主要荧光峰均出现在较长波长处。FA荧光光谱特征参数分析表明，各点位富里酸腐殖化程度为：HXXD>HXDX>HXDB>HXXX。其中HXXD点位FA以陆源输入为主，而其他点位FA则陆源与水生生物源并存。利用荧光区域积分(FRI)技术，对FA的三维荧光光谱5个区域(Ⅰ-Ⅴ)的荧光响应值比例(percent fluorescence response, P_{i, n})比较证实，所有点位类胡敏酸区域(Ⅴ区)的P_{Ⅴ, n}、类富里酸(Ⅲ区)的P_{Ⅲ, n}均占有较大的比例，同时采用三维荧光区域积分法判断各点位FA腐殖化程度与二维荧光特性结论一致。三维荧光光谱中r_{(A, C)}值与区域积分(FRI)中P_{Ⅴ, n}/P_{Ⅲ, n}及(P_{Ⅴ, n}+P_{Ⅲ, n})/(P_{Ⅰ, n}+P_{Ⅱ, n}+P_{Ⅲ, n})均具有显著的相关性，因此，r_{(A, C)}值是兴凯湖沉积物FA腐殖程度表征的一个方便、快捷的参数。

Studies on Fluorescence Spectral Characteristics of Fulvic Acid (FA) from Xingkai Lake Sediments

Four samples (sample No. HXXD, HXXX, HXDX and HXDB) were taken from Xingkai Lake Sediments in Heilongjiang province and fluorescence spectral characteristics of Fulvic acid (FA) from sediments were studied. Conventional and excitation-emission matrix (EEM) all indicated that FA from HXXD sediment exhibited primary peaks at longer wavelengths. The analysis of fluorescence characteristic parameters indicated that the degree of humification of FA from all sample points were in the order: HXXD>HXDX>HXDB>HXXX. Fluorescence index (f_450/500) suggested that FA from HXXD mainly originated from terrestrial sources, while the FA from other samples mainly originated from aquatic organism sources and terrestrial sources. Based on EEM fluorescence regional integration (FIR), the percent fluorescence responses (P_{i, n}) of five regions in 3EEMs was calculated. The distributions of P_{Ⅴ, n} (humic acid-like region) and P_{Ⅲ, n} (fulvic acid-like region) were the largest in all samples. The conclusion of the degree of humification of FA based on FIR was consistent with the analysis of conventional fluorescence parameters. The correlation analysis showed that, r_{(A, C)} was significantly correlative with P_{Ⅴ, n}/P_{Ⅲ, n}, (P_{Ⅴ, n}+P_{Ⅲ, n})/(P_{Ⅰ, n}+P_{Ⅱ, n}+P_{Ⅲ, n}) and P_{Ⅴ, n}. The results suggest that r_{(A, C)} index is a reasonable tool for assessing humification degree of FA from Xingkai Lake sediments.