{"title":"荧光和吸收率测量作为溶解有机物分子量和芳香性替代物的批判性评述","authors":"Julie A. Korak and Garrett McKay","doi":"10.1039/D4EM00183D","DOIUrl":null,"url":null,"abstract":"<p >Dissolved organic matter (DOM) is ubiquitous in aquatic environments and challenging to characterize due to its heterogeneity. Optical measurements (<em>i.e.</em>, absorbance and fluorescence spectroscopy) are popular characterization tools, because they are non-destructive, require small sample volumes, and are relatively inexpensive and more accessible compared to other techniques (<em>e.g.</em>, high resolution mass spectrometry). To make inferences about DOM chemistry, optical surrogates have been derived from absorbance and fluorescence spectra to describe differences in spectral shape (<em>e.g.</em>, E2:E3 ratio, spectral slope, fluorescence indices) or quantify carbon-normalized optical responses (<em>e.g.</em>, specific absorbance (SUVA) or specific fluorescence intensity (SFI)). The most common interpretations relate these optical surrogates to DOM molecular weight or aromaticity. This critical review traces the genesis of each of these interpretations and, to the extent possible, discusses additional lines of evidence that have been developed since their inception using datasets comparing diverse DOM sources or strategic endmembers. This review draws several conclusions. More caution is needed to avoid presenting surrogates as specific to either molecular weight or aromaticity, as these physicochemical characteristics are often correlated or interdependent. Many surrogates are proposed using narrow contexts, such as fractionation of a limited number of samples or dependence on isolates. Further study is needed to determine if interpretations are generalizable to whole-waters. Lastly, there is a broad opportunity to identify why endmembers with low abundance of aromatic carbon (<em>e.g.</em>, effluent organic matter, Antarctic lakes) often do not follow systematic trends with molecular weight or aromaticity as observed in endmembers from terrestrial environments with higher plant inputs.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 10","pages":" 1663-1702"},"PeriodicalIF":4.3000,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/em/d4em00183d?page=search","citationCount":"0","resultStr":"{\"title\":\"Critical review of fluorescence and absorbance measurements as surrogates for the molecular weight and aromaticity of dissolved organic matter†\",\"authors\":\"Julie A. 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引用次数: 0
摘要
溶解有机物(DOM)在水生环境中无处不在,由于其异质性,对其进行表征具有挑战性。光学测量(即吸光度和荧光光谱)是常用的表征工具,因为它们不具破坏性,所需样本量小,而且相对便宜,与其他技术(如高分辨率质谱法)相比更容易获得。为了推断 DOM 化学性质,人们从吸收光谱和荧光光谱中推导出光学代用指标,以描述光谱形状的差异(如 E2:E3 比值、光谱斜率、荧光指数)或量化碳归一化光学响应(如特定吸收光谱(SUVA)或特定荧光强度(SFI))。最常见的解释是将这些光学代用指标与 DOM 分子量或芳香度联系起来。本评论追溯了每种解释的起源,并尽可能讨论了自这些解释出现以来,利用比较不同 DOM 来源或战略内含物的数据集开发出的其他证据。本综述得出了几个结论。需要更加谨慎,避免把代用指标说成是分子量或芳香度的特异性指标,因为这些理化特征往往是相互关联或相互依存的。许多代用指标都是在狭窄的范围内提出的。例如,对数量有限的样本进行分馏或依赖于分离物并将解释推广到整个水体的做法值得进一步研究。最后,我们还有很多机会来确定为什么芳香碳含量较低的内含物(如南极湖泊中的排出有机物)通常不会像植物投入量较高的陆地环境中的内含物那样,随着分子量或芳香度的增加而呈现系统化趋势。
Critical review of fluorescence and absorbance measurements as surrogates for the molecular weight and aromaticity of dissolved organic matter†
Dissolved organic matter (DOM) is ubiquitous in aquatic environments and challenging to characterize due to its heterogeneity. Optical measurements (i.e., absorbance and fluorescence spectroscopy) are popular characterization tools, because they are non-destructive, require small sample volumes, and are relatively inexpensive and more accessible compared to other techniques (e.g., high resolution mass spectrometry). To make inferences about DOM chemistry, optical surrogates have been derived from absorbance and fluorescence spectra to describe differences in spectral shape (e.g., E2:E3 ratio, spectral slope, fluorescence indices) or quantify carbon-normalized optical responses (e.g., specific absorbance (SUVA) or specific fluorescence intensity (SFI)). The most common interpretations relate these optical surrogates to DOM molecular weight or aromaticity. This critical review traces the genesis of each of these interpretations and, to the extent possible, discusses additional lines of evidence that have been developed since their inception using datasets comparing diverse DOM sources or strategic endmembers. This review draws several conclusions. More caution is needed to avoid presenting surrogates as specific to either molecular weight or aromaticity, as these physicochemical characteristics are often correlated or interdependent. Many surrogates are proposed using narrow contexts, such as fractionation of a limited number of samples or dependence on isolates. Further study is needed to determine if interpretations are generalizable to whole-waters. Lastly, there is a broad opportunity to identify why endmembers with low abundance of aromatic carbon (e.g., effluent organic matter, Antarctic lakes) often do not follow systematic trends with molecular weight or aromaticity as observed in endmembers from terrestrial environments with higher plant inputs.
期刊介绍:
Environmental Science: Processes & Impacts publishes high quality papers in all areas of the environmental chemical sciences, including chemistry of the air, water, soil and sediment. We welcome studies on the environmental fate and effects of anthropogenic and naturally occurring contaminants, both chemical and microbiological, as well as related natural element cycling processes.