- Composition Characteristics and Source of Chromophoric Dissolved Organic Matter in Poyang Lake Wetland Based on Three-dimensional Fluorescence Excitation-Emission Matrix Spectroscopy
- 摘要：有色可溶性有机物(chromophoric dissolved organic matter, CDOM)是水生生态系统的重要组成部分，在生物地球化学循环过程中起着重要的作用。本研究基于2021年4月鄱阳湖南矶湿地国家级自然保护区内3个碟形湖(战备湖、白沙湖和东湖)28个采样点的水样和实测水质参数数据，运用紫外-可见吸收光谱及三维荧光光谱-平行因子分析法(three-dimensional fluorescence excitation-emission matrix spectroscopy-parallel factor analysis, 3DEEMs-PARAFAC)分析了鄱阳湖湿地水体CDOM组成特征及潜在来源。结果表明：(1)通过对28个激发-发射矩阵光谱进行平行因子分析，得到两种类腐殖质荧光组分C1(240 nm, 315 nm/403 nm)、C2(275 nm, 350 nm/476 nm)和一种类色氨酸荧光组分C3(230 nm, 280 nm/338 nm)，并且类腐殖质荧光组分(C1+C2)和类色氨酸荧光组分C3对总荧光强度的贡献率分别为70.13%和29.87%。(2)鄱阳湖湿地水体CDOM荧光组分C1?C3最大荧光强度(Fmax)的平均值均表现为东湖>战备湖>白沙湖，且三个荧光组分呈现正相关(p?0.001)，说明其来源类似。(3)基于荧光指数(fluorescence index, FI)、腐殖化指数(humification index, HIX)、E2/E3(CDOM在波长250 nm和365 nm处的吸收系数(ag(250))与(ag(365))的比值)和光谱斜率等特征参数分析，得到鄱阳湖湿地水体CDOM有较强腐殖质特征，以陆源输入为主。
- Abstract：Chromophoric dissolved organic matter (CDOM) is an important part of aquatic ecosystem and plays a key role in the biogeochemical cycle. In this study, the data of water samples and water quality parameters from 28 sampling sites of three sub-lakes (Zhanbei lake, Baisha lake and Dong lake) in Nanji Wetland National Nature Reserve of Poyang Lake were collected in April 2021. Composition characteristics and sources of CDOM in the water of Poyang Lake wetland were analyzed by ultraviolet-visible absorption spectrum and three-dimensional fluorescence excitation-emission matrix spectroscopy-parallel factor analysis (3DEEMs-PARAFAC). The results showed that: (1) Three fluorescent components, including two humic-like components C1 (240 nm, 315 nm/403 nm), C2 (275 nm, 350 nm/476 nm) and one tryptophan-like component C3 (230 nm, 280 nm/338 nm) were obtained by parallel factor analysis of 28 excitation-emission matrix spectra. The contribution rates to the total fluorescence intensity of humic-like components (C1+C2) and tryptophan-like component C3 were 70.13% and 29.87%, respectively. (2) The average value of the maximum fluorescence intensity (Fmax) of CDOM fluorescence components C1 ? C3 in Poyang Lake wetland followed the spatial pattern of Dong lake > Zhanbei lake > Baisha lake. All the three components showed significant positive correlations (p ? 0.001) with each other. This result indicated that the CDOM in Poyang Lake wetland may have the similar sources. (3) The analysis of the spectral characteristic parameters of fluorescence index (FI), humification index (HIX), E2/E3 (the ratio of the CDOM absorption coefficient at a wavelength of 250 nm to the CDOM absorption coefficient at a wavelength of 365 nm) and spectral slopes showed that the CDOM in Poyang Lake wetland had relatively high humus, which were mainly affected by terrestrial inputs.