利用紫外-可见光光谱技术(UV-Vis)和三维荧光光谱(3D EEMs)技术,结合平行因子分析法(PARAFAC),研究了巢湖表层沉积物溶解性有机氮(Dissolved Organic Nitrogen,DON)结构组分及其来源.结果表明:巢湖表层沉积物中DON主要以亲水性物质存在,芳香环取代基以脂肪链为主,腐殖化程度较低.PARAFAC共识别出3类荧光组分,分别是类腐殖质组分C1,类蛋白组分C2和类腐殖质组分C3,其中3个组分均与总溶解态氨基酸(Dissolved Total Amino Acids,DTAA)和游离氨基酸(Dissolved Free Amino Acids,DFAA)存在相关性,类蛋白组分占比高于类腐殖质组分,且C1、C2、C3具有相似的结构或来源,可作为不同氮形态含量的指标.巢湖表层沉积物DON空间分布、芳香性、腐殖化程度、溶解性有机质分子质量、3个荧光组分的强度、类蛋白质组分浓度以及类腐殖质组分浓度均呈现出西湖区＞东湖区＞中湖区,与巢湖的污染水平和富营养化程度有相似的空间分布特征.荧光特征指数表明巢湖表层沉积物DON受内源与外源的共同影响,但自生源特征较强.
Spectroscopic Characteristics of Dissolved Organic Nitrogen in Surface Sediments from Lake Chaohu
Using ultraviolet-visible spectroscopy(UV-Vis)and three-dimensional fluorescence spectroscopy(3D EEMs)combined with parallel factor analysis(PARAFAC),the structural components and sources of dissolved organic nitrogen(DON)in surface sediments of Lake Chaohu were investigated.The results show that DON in the surface sediments of Lake Chaohu mainly exists as hydrophilic substances,with aromatic ring substituents being dominated by aliphatic chains and a relatively low degree of humification.PARAFAC identified three fluorescent components,namely,humic-like component C1,protein-like component C2,and humic-like component C3.All three components were correlated with dissolved total amino acids(DTAA)and dissolved free amino acids(DFAA).The proportion of protein-like components was higher than that of humic-like components,and C1,C2,and C3 had similar structures or sources,which could serve as indicators of different nitrogen forms.The spatial distribution of DON in surface sediments of Lake Chaohu,aromaticity,degree of humification,molecular weight of dissolved organic matter,intensity of the three fluorescent components,concentration of protein-like components,and concentration of humic-like components all show a pattern of West Lake area＞East Lake area＞Central Lake area,similar to the pollution level and eutrophication degree of Lake Chaohu.Fluorescence characteristic indices indicate that the DON in surface sediments of Lake Chao is influenced by both endogenous and exogenous factors,but with a stronger endogenous characteristic.
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