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首页> 外文期刊>Environmental Science & Technology >Optical Properties of Soil Dissolved Organic Matter Are Related to Acidic Functions of Its Components as Revealed by Fractionation, Selective Deuteromethylation, and Ultrahigh Resolution Mass Spectrometry
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Optical Properties of Soil Dissolved Organic Matter Are Related to Acidic Functions of Its Components as Revealed by Fractionation, Selective Deuteromethylation, and Ultrahigh Resolution Mass Spectrometry

机译：分馏，选择性氘代甲基化和超高分辨率质谱表明，土壤中溶解的有机物的光学性质与其组分的酸性功能有关。

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摘要

The goal of this study was to establish a relationship between the optical properties of soil dissolved organic matter (DOM) and acidic functions carried out by its individual constituents. We obtained 12 fractions of DOM samples using sequential solid phase extraction on nonionic sorbent at steadily lowered pH values: 7, 5, 3, 2, which correspond to low bounds of pK_a values of phenols, aliphatic, and aromatic carboxylic acids, and ketoacids. The structural studies were conducted with the use of NMR and selective deuteromethylation of isolated fractions coupled to ultrahigh resolution mass spectrometry. First, a gradual shift of molecular compositions was observed from reduced components to aromatic oxidized compounds isolated at pH 7 and 2, respectively. Changes in molecular compositions were accompanied by a red shift of fluorescence spectra. Further application of deuteromethylation enabled us to distinguish DOM constituents with different amounts of carboxylic groups. Moreover, identification of structural isomers in a single DOM sample was achieved. Statistical analysis revealed that red shift of fluorescence is facilitated by the increase of a contribution of aromatic poly(carboxylic acid)s with high conjugation lengths. Additionally, analysis of the labeled fractionated permafrost thaw DOM directly showed carboxyl-rich alicyclic molecules, while the same components from lower-latitude DOM were assigned to lignin-like species.
机译：这项研究的目的是建立土壤可溶性有机物（DOM）的光学特性与其单独成分所实现的酸性功能之间的关系。我们在非离子吸附剂上采用连续固相萃取在稳定降低的pH值（7、5、3、2）下获得了12份DOM样品，这对应于苯酚，脂肪族和芳香族羧酸以及酮酸的pK_a值的下限。结构研究是通过使用NMR和分离的级分的选择性氘代甲基化与超高分辨率质谱联用进行的。首先，观察到分子组成从还原组分逐渐转移到分别在pH 7和2下分离的芳族氧化化合物。分子组成的变化伴随着荧光光谱的红移。氘代甲基化的进一步应用使我们能够区分具有不同数量羧基的DOM成分。此外，实现了单个DOM样品中结构异构体的鉴定。统计分析表明，高共轭长度的芳香族聚羧酸的贡献的增加促进了荧光的红移。此外，对标记的分级永冻土DOM的分析直接显示了富含羧基的脂环族分子，而来自低纬度DOM的相同成分则被分配为木质素样物质。

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  • 来源
    《Environmental Science & Technology》 |2020年第5期|2667-2677|共11页
  • 作者

    Alexander Zherebker; Evgeny Shirshin; Anna Rubekina; Oleg Kharybin; Alexey Kononikhin; Natalia A. Kulikova; Kirill V. Zaitsev; Vitaliy A Roznyatovsky; Yuri K. Grishin; Irina V. Perminova; Evgeny N. Nikolaev;

  • 作者单位

    Skolkovo Institute of Science and Technology Skolkovo Moscow Region 14302S Russia Department of Chemistry Lomonosov Moscow State University Moscow 119991 Russia;

    Department of Physics Lomonosov Moscow State University Moscow 119991 Russia;

    Skolkovo Institute of Science and Technology Skolkovo Moscow Region 14302S Russia;

    Department of Soil Science Lomonosov Moscow State University Moscow 119991 Russia Federal Research Center "Fundamentals of Biotechnology" Bakh Institute of Biochemistry Russian Academy of Sciences Moscow 119071 Russia;

    Department of Chemistry Lomonosov Moscow State University Moscow 119991 Russia;

    Skolkovo Institute of Science and Technology Skolkovo Moscow Region 14302 Russia;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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