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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >A coupled geochemical and biogeochemical approach to characterize the bioreactivity of dissolved organic matter from a headwater stream
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A coupled geochemical and biogeochemical approach to characterize the bioreactivity of dissolved organic matter from a headwater stream

机译：结合地球化学和生物地球化学方法来表征源头水流中溶解的有机物的生物反应性

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The bioreactivity or susceptibility of dissolved organic matter (DOM) to microbial degradation in streams and rivers is of critical importance to global change studies, but a comprehensive understanding of DOM bioreactivity has been elusive due, in part, to the stunningly diverse assemblages of organic molecules within DOM. We approach this problem by employing a range of techniques to characterize DOM as it flows through biofilm reactors: dissolved organic carbon (DOC) concentrations, excitation emission matrix spectroscopy (EEMs), and ultrahigh resolution mass spectrometry. The EEMs and mass spectral data were analyzed using a combination of multivariate statistical approaches. We found that 45% of stream water DOC was biodegraded by microorganisms, including 31-45% of the humic DOC. This bioreactive DOM separated into two different groups: (1) H/C centered at 1.5 with O/C 0.1-0.5 or (2) low H/C of 0.5-1.0 spanning O/C 0.2-0.7 that were positively correlated (Spearman ranking) with chromophoric and fluorescent DOM (CDOM and FDOM, respectively). DOM that was more recalcitrant and resistant to microbial degradation aligned tightly in the center of the van Krevelen space (H/C 1.0-1.5, O/C 0.25-0.6) and negatively correlated (Spearman ranking) with CDOM and FDOM. These findings were supported further by principal component analysis and 2-D correlation analysis of the relative magnitudes of the mass spectral peaks assigned to molecular formulas. This study demonstrates that our approach of processing stream water through bioreactors followed by EEMs and FTICR-MS analyses, in combination with multivariate statistical analysis, allows for precise, robust characterization of compound bioreactivity and associated molecular level composition.
机译：溶解性有机物（DOM）对溪流和河流中微生物降解的生物反应性或敏感性对于全球变化研究至关重要，但是对DOM生物反应性的全面了解一直难以捉摸，部分原因是有机分子的惊人多样性在DOM中。我们通过采用一系列技术来表征DOM流经生物膜反应器的方法来解决此问题：溶解有机碳（DOC）浓度，激发发射矩阵光谱（EEM）和超高分辨率质谱。使用多元统计方法的组合分析了EEM和质谱数据。我们发现45％的溪流DOC被微生物生物降解，包括31-45％的腐殖DOC。这种生物反应性DOM分为两个不同的组：（1）H / C以1.5为中心，O / C为0.1-0.5或（2）0.5 / 1.0的低H / C，O / C为0.2-0.7呈正相关（Spearman有色和荧光DOM（分别为CDOM和FDOM）。 DOM具有更强的抵抗性和抗微生物降解性，在van Krevelen空间的中心紧密对齐（H / C 1.0-1.5，O / C 0.25-0.6），与CDOM和FDOM负相关（Spearman排名）。这些发现进一步得到了主成分分析和二维峰相关值的定量相关分析的支持，这些质谱峰分配给分子式。这项研究表明，我们通过生物反应器处理水流，然后进行EEM和FTICR-MS分析的方法，与多元统计分析相结合，可以对化合物生物反应性和相关的分子水平组成进行精确，可靠的表征。

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