应用多元统计研究蘑菇湖水体DOM紫外光谱特征

摘要

UV-Vis spectroscopy combined with multivariate statistics was applied to explore the composition and structures of dissolved organic matter (DOM) from the Moguhu Lake, identify the sources, and evaluate DOM humification degree.The results show that: (1) The DOM in the lake was mainly composed of non-polar functional groups such as aliphatic chains and esters, and exogenous humic acid with relatively large molecular mass.The humification degree of the DOM decreased from the shallow region to the deep region in the lake. (2) There were positive correlations among A (250 nm) /A (365 nm), A (240 nm) /A (420 nm) and A3/A2, and relatively positive correlations among A (465 nm) /A (665 nm), SR, A2/A1and A3/A1.Furthermore, the former indices showed significantly negative correlations with the latter indices.These indicated that the humification degree of DOM was closely associated with the molecular weights, aromaticity and condensation of the benzene ring carbon skeleton. (3) The canonical correspond analysis (CCA) results showed that there was a certain correlation between the sampling points of Moguhu Lake, the aromaticity and humification degree of DOM, which was similar to Pearson's correlation analysis.To a certain extent, studies have shown that UV-Vis, spectral index and multivariate statistical analysis can to some extent characterize the molecular weight, aromaticity and degree of humus of DOM in Moguhu Lake.%为了探究蘑菇湖水体中DOM(溶解性有机物)的组成和结构特征、识别来源及表征腐殖化程度,采用UV-Vis(紫外-可见吸收光谱)和紫外吸收光谱指数、多元统计分析方法对蘑菇湖水体DOM进行表征.结果表明:(1)蘑菇湖水体DOM腐殖化程度由滨湖区向深湖区递减,DOM主要以脂肪链和酯类等非极性官能团及相对分子质量较大的外源胡敏酸为主.(2)皮尔逊相关性分析发现,A(250 nm)/A(365 nm)、A(240 nm)/A(420 nm)与A3/A2(600～700 nm与460～480 nm波段下的积分面积之比)之间呈显著正相关,A(465 nm)/A(665 nm)、SR[光谱斜率比,Sg(275～295 nm)/Sg(350～400 nm)]、A2/A1(460～480 nm与260～280 nm波段下的积分面积之比)与A3/A1(600～700 nm与260～280 nm波段下的积分面积之比)之间也均呈显著正相关,而二者之间呈负相关,表明蘑菇湖水体中DOM的腐殖化水平与有机质的相对分子质量、芳香度以及苯环碳骨架的聚合程度等密切相关.(3)CCA(canonical correspond analysis,典范对应分析)结果发现,蘑菇湖水体采样点与DOM的芳香度、腐殖化程度存在一定的相关性,与皮尔逊相关性分析结果相似.研究显示,UV-Vis、紫外吸收光谱指数、多元统计分析能够在一定程度上表征蘑菇湖水体DOM的分子量、芳香度以及腐殖化程度.