Marine dissolved organic matter (DOM) is one of the largest reservoirs of organic carbon and nitrogen in the world. Yet, despite its global importance, most DOM remains molecularly uncharacterized. Solid-state nuclear magnetic resonance (NMR) spectroscopy of isolated DOM fractions represents one of the most powerful techniques to understand overall structural composition. However, it is well known that standard cross polarization magic angle spinning (CP/MAS) NMR, the technique used for almost all past solid-state NMR studies of DOM, is at best “semi-quantitative,” and underestimates fully substituted NMR active nuclei. Additionally, almost all past solid-state NMR work analyzed high molecular weight (HMW) material isolated by ultrafiltration, which is now understood to represent mostly 14C-young, “semi-labile” compounds. In contrast, there is far less information regarding the composition of older, low molecular weight (LMW) DOM, which represents the vast majority of the ocean’s accumulated refractory DOM pool.

中文翻译：

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改进的固态 13C 和 15N NMR 揭示了海洋中难降解溶解有机碳和氮之间的基本成分差异


海洋可溶性有机物 （DOM） 是世界上最大的有机碳和氮储层之一。然而，尽管 DOM 具有全球重要性，但大多数 DOM 仍未进行分子表征。孤立的 DOM 组分的固体核磁共振 （NMR） 波谱是了解整体结构组成的最强大技术之一。然而，众所周知，标准的交叉极化魔角旋转 （CP/MAS） NMR，过去几乎所有用于 DOM 固体 NMR 研究的技术，充其量是“半定量的”，并且低估了完全取代的 NMR 活性核。此外，几乎所有过去的固体核磁共振工作都分析了通过超滤分离的高分子量 （HMW） 材料，现在人们认为这些材料主要代表 14C 年轻的“半不稳定”化合物。相比之下，关于较老的低分子量 （LMW） DOM 组成的信息要少得多，它代表了海洋积累的耐火材料 DOM 库的绝大多数。