A molecular perspective on the ageing of marine dissolved organic matter
A molecular perspective on the ageing of marine dissolved organic matter
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DOI：
10.5194/bg-9-1935-2012
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发表时间：
2012-01-01
期刊：
影响因子：
4.9
通讯作者：
Kattner, G.
中科院分区：
文献类型：
--
作者：
Flerus, R.;Lechtenfeld, O. J.;Kattner, G.
采用固相萃取法（SPE）提取了东大西洋断面沿着不同气候带、不同深度的137个水样中的溶解有机质（DOM）。提取物采用傅里叶变换离子回旋共振质谱（FT-ICR MS）和电喷雾电离（ESI）进行分析。对SPE-DOM的子样本进行Δ C-14分析。此外，溶解的有机碳的量被确定为所有的水和SPE-DOM样品，以及氨基糖的产率为选定的样品。在43%的FT-ICR质量峰的幅度和提取物Δ C-14值之间观察到线性相关性。SPE-DOM Δ C-14值的降低沿着分子组成向更高的平均质量（m/z）和更低的氢/碳（H/C）比的转变。相关性用于模拟所有137个样品的SPE-DOM Delta C-14分布。基于单质量峰，建立了一个降解指数（I-DEG），用于比较FT-ICR MS分析的海洋SPE-DOM样品的降解状况。DOM加权归一化质量峰幅度被用来比较年龄和最近SPE-DOM的半定量分子的基础上。幅度比较显示，检测到的化合物具有连续的不同降解速率。在温盐循环过程中，高比例的化合物应持续存在，可能会因部分降解而改变。这种非常稳定的DOM主要在海洋上层产生、转化和积累。这个DOM是对非常古老的DOM的重要贡献，表明生产和退化是动态过程。
Dissolved organic matter (DOM) was extracted by solid-phase extraction (SPE) from 137 water samples from different climate zones and different depths along an eastern Atlantic Ocean transect. The extracts were analyzed with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with electrospray ionization (ESI). Delta C-14 analyses were performed on subsamples of the SPE-DOM. In addition, the amount of dissolved organic carbon was determined for all water and SPE-DOM samples as well as the yield of amino sugars for selected samples. Linear correlations were observed between the magnitudes of 43% of the FT-ICR mass peaks and the extract Delta C-14 values. Decreasing SPE-DOM Delta C-14 values went along with a shift in the molecular composition to higher average masses (m/z) and lower hydrogen/carbon (H/C) ratios. The correlation was used to model the SPE-DOM Delta C-14 distribution for all 137 samples. Based on single mass peaks, a degradation index (I-DEG) was developed to compare the degradation state of marine SPE-DOM samples analyzed with FT-ICR MS. A correlation between Delta C-14, IDEG, DOC values and amino sugar yield supports that SPE-DOM analyzed with FT-ICR MS reflects trends of bulk DOM. DOM weighted normalized mass peak magnitudes were used to compare aged and recent SPE-DOM on a semi-quantitative molecular basis. The magnitude comparison showed a continuum of different degradation rates for the detected compounds. A high proportion of the compounds should persist, possibly modified by partial degradation, in the course of thermohaline circulation. Prokaryotic (bacterial) production, transformation and accumulation of this very stable DOM occur primarily in the upper ocean. This DOM is an important contribution to very old DOM, showing that production and degradation are dynamic processes.