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首页> 外文学位 >High resolution molecular characterization of photochemical and microbial transformation of dissolved organic matter in temperate streams of different watershed land use.
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High resolution molecular characterization of photochemical and microbial transformation of dissolved organic matter in temperate streams of different watershed land use.

机译：不同流域土地利用的温带河流中溶解有机物的光化学和微生物转化的高分辨率分子表征。

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摘要

The objective of the present study was to provide better understanding of the effects of watershed land use on molecular composition of streamwater DOM and molecular transformations associated with photochemical and microbial processing of DOM. We compared DOM from headwater streams draining forest-dominated watersheds (FW) and pasture-dominated watersheds (PW) in the lower Chesapeake Bay region (Virginia, USA). Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry analysis was conducted on streamwater DOM prior to and after laboratory incubations: 1) bacteria-only incubations; 2) light-only incubations; and 3) combined light+bacterial incubations. Results showed that DOM in FW streams and PW streams differed in molecular characteristics---the former was characterized by greater structural complexity and aromaticity, higher proportions of condensed aromatic molecules and black carbon-like components, while the latter was higher in the proportions of lipid-like components, protein-like components and aliphatic compounds. Relative to DOM from FW streams, DOM from PW streams was more reactive to bacterial transformation. Protein-like components, lipid-like components and unsaturated hydrocarbon-like components are primarily responsible for the changes associated with bacterial transformation of DOM. However, similar behavior was also observed for DOM in FW streams and PW streams under the influence of bacterial and photochemical processes. Bacterial transformation reduced the proportions of lipid-like components but increased the proportions of lignin-like components and carboxyl-rich alicyclic molecule-like components, indicating that lipid-like components was a bioreactive class while lignin-like components and carboxyl-rich alicyclic were resistant to bacterial processing. Photochemical processes, alone or combined with microbial alterations, increased the proportions of protein-like components, which may be due to the light stimulation of autochthonous production of protein-like components, and increased the relative abundance of carboxyl-rich alicyclic molecule-like components, which indicates the refractory nature of these molecules. Photochemical processes also significantly reduced the amount of dissolved black carbon-like components, which suggests dissolved black carbon was a photoreactive class, countering the conventional view that black carbon was an inter group in carbon cycle. Collectively, these findings suggest that human land use in upstream watersheds may lead to alterations to the molecular composition of streamwater DOM as well as to its behavior to photochemical and microbial processing.
机译：本研究的目的是更好地了解流域土地利用对河流DOM分子组成的影响以及与DOM的光化学和微生物加工有关的分子转化。我们比较了切萨皮克湾下游地区（美国弗吉尼亚州）的流源性森林支配流域（FW）和牧场支配流域（PW）的上游水流中的DOM。在实验室培养之前和之后，对水域DOM进行电喷雾电离傅里叶变换离子回旋共振质谱分析：1）仅细菌培养； 2）仅孵化器； 3）光+细菌培养。结果表明FW流和PW流中的DOM的分子特性不同-前者的特征是结构复杂性和芳香性更高，缩合的芳族分子和黑碳状组分的比例更高，而后者的比例更高。类脂质成分，类蛋白质成分和脂肪族化合物。相对于FW流中的DOM，PW流中的DOM对细菌转化更具反应性。蛋白样成分，脂质样成分和不饱和烃样成分主要负责与DOM细菌转化有关的变化。但是，在细菌和光化学过程的影响下，FW流和PW流中的DOM也观察到类似的行为。细菌转化减少了类脂质成分的比例，但增加了木质素类成分和富含羧基的脂环族分子类成分的比例，表明类脂成分是生物反应性类别，而木质素类成分和富含羧基的脂环族成分则具有生物反应性。耐细菌加工。光化学过程（单独或与微生物改变结合）增加了蛋白质样组分的比例，这可能是由于光刺激蛋白质样组分的自发产生，并增加了富含羧基的脂环式分子样组分的相对丰度，表明这些分子的难熔性。光化学过程还显着减少了溶解的类黑碳成分的含量，这表明溶解的黑碳属于光反应性类，这与传统观点认为黑碳是碳循环中的一个中间基团的观点相反。总体而言，这些发现表明上游流域的人类土地利用可能导致溪流DOM的分子组成及其对光化学和微生物加工的行为发生改变。

著录项

  • 作者

    Li, Xiaping.;

  • 作者单位

    The University of Alabama.;

  • 授予单位 The University of Alabama.;
  • 学科 Geochemistry.;Environmental Geology.;Chemistry Biochemistry.
  • 学位 M.S.
  • 年度 2014
  • 页码 74 p.
  • 总页数 74
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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