雄安新区-白洋淀冬季冰封期水体溶解性有机物的空间分布、光谱特征及来源解析

运用三维荧光光谱(EEMs)技术结合平行因子分析法(PARAFAC)以及紫外-可见光谱技术(UV-vis),对雄安新区-白洋淀冬季冰封期不同特征区域水体溶解性有机物(DOM)的空间分布、光谱特征以及来源进行解析.结果表明,冬季冰封期白洋淀水体DOM吸收系数无特征峰,不同特征区域的差异显著;表层水体DOM与底层水体DOM的吸收系数差异不明显;冰封期白洋淀水体的E3/E4均大于3. 5,说明DOM以低腐殖质成分为主,E2/E3为6. 35±0. 72,表明DOM中小分子量的居多,而且SR为1. 33±0. 14均大于1,显示DOM主要为生物源;三维荧光通过PARAFAC解析出3种组分,分别为类酪氨酸(C1)、类色氨酸(C2)和陆源腐殖质(C3);对3个组分进行相关性分析,结果显示C1与C2之间具有显著的相关性(P 0. 001);白洋淀各个特征区域间的DOM总荧光强度和各荧光组分荧光强度呈现显著的差异(P 0. 01); DOM的总荧光强度以及各组分的荧光强度均呈现出唐河入淀口高、烧车淀低的特征,C1+C2是DOM的主要成分;冰封期白洋淀水体的DOM生物源指数(BIX)为1. 23±0. 18,荧光指数FI为2. 30±0. 16 ( 1. 8),表明白洋淀DOM来源于生物活动并且以自生源为主,与腐殖程度指标(HIX)的结果相吻合; PCA结合Adonis分析显示,白洋淀不同区域水体DOM的光谱特征差异明显(P 0. 05),表层与底层的DOM光谱特征相近(P 0. 05);并且组分C1、C2、C3与DOM特征参数(HIX、BIX、Fn280、Fn355)以及水质参数(总氮、高锰酸盐指数、溶解性总磷)构建的多元线性回归方程显著相关性(P 0. 001).综上,通过对冬季冰封期白洋淀各个典型淀区水体DOM光谱特征进行研究,可以为分析白洋淀水体有机物污染特征和白洋淀的水质管理提供技术支持.

Spatial Distribution, Spectral Characteristics, and Sources Analysis of Dissolved Organic Matter from Baiyangdian Lake in Xiong'an New District During the Winter Freezing Period

Based on excitation emission matrix spectroscopy (EEMs) technology combined with parallel factor analysis (PARAFAC) and ultraviolet-visible (UV-vis) spectra, we analyze the spatial distribution, spectral characteristics, and sources of dissolved organic matter (DOM) in Baiyangdian Lake, China, during a winter freezing period. Results showed that the UV-vis absorption spectrum of DOM had no obvious characteristic peak, and that the variation coefficient of absorption exhibited a significant difference (P<0.05) among different districts of Baiyangdian Lake, but that there was no significant difference between the surface and bottom waters. The changes of E3/E4, E2/E3, and S_R showed that DOM had low humic and autochthonous characteristics. Two protein-like substances (C1 and C2) and one humic-like substance (C3) were identified by PARAFAC, with a significant correlation (P<0.001) being found between C1 and C3, and C2 and C3. The total DOM fluorescence intensity and the fluorescence intensity of each component exhibited significant differences (P<0.01) in the distribution among the different districts of Baiyangdian Lake, with the maximum value being associated with a sample from the Tanghe River and the minimum value being associated with a sample from Shaochedian. Moreover, the sum of C1+C2 accounted for the major proportion of DOM. DOM exhibited a strong autochthonous characteristic based on the values of BIX, FI, and HIX. Principle component analysis (PCA) and Adonis analysis showed that the spectral characteristics of DOM exhibited a significant difference (P<0.05) among the different districts. C1, C2, and C3 were significantly correlated (P<0.001) with DOM indices (HIX, BIX, Fn280, and Fn355) and water quality parameterstotal nitrogen (TN), permanganate index, and total dissolved phosphorus (TDP)] based on multiple linear regression. Our results contribute to previous investigations and provide findings that can assist in the future management and control of organic carbon pollution sources to Baiyangdian Lake.