Lam Buuan, Baer Andrew, Alaee Mehran, Lefebvre Brent, Moser Arvin, Williams Antony, Simpson André J
Department of Chemistry, University of Toronto Scarborough, Toronto, Ontario, Canada M1C 1A4.
Environ Sci Technol. 2007 Dec 15;41(24):8240-7. doi: 10.1021/es0713072.
Dissolved organic matter (DOM) contains a complex array of chemical components that are intimately linked to many environmental processes, including the global carbon cycle, and the fate and transport of chemical pollutants. Despite its importance, fundamental aspects, such as the structural components in DOM remain elusive, due in part to the molecular complexity of the material. Here, we utilize multidimensional nuclear magnetic resonance spectroscopy to demonstrate the major structural components in Lake Ontario DOM. These include carboxyl-rich alicyclic molecules (CRAM), heteropolysaccharides, and aromatic compounds, which are consistent with components recently identified in marine dissolved organic matter. In addition, long-range proton-carbon correlations are obtained for DOM, which support the existence of material derived from linear terpenoids (MDLT). It is tentatively suggested that the bulk of freshwater dissolved organic matter is aliphatic in nature, with CRAM derived from cyclic terpenoids, and MDLT derived from linear terpenoids. This is in agreement with previous reports which indicate terpenoids as major precursors of DOM. At this time it is not clear in Lake Ontario whether these precursors are of terrestrial or aquatic origin or whether transformations proceed via biological and/ or photochemical processes.
溶解有机物（DOM）包含一系列复杂的化学成分，这些成分与许多环境过程密切相关，包括全球碳循环以及化学污染物的归宿和迁移。尽管其很重要，但由于该物质的分子复杂性，DOM的一些基本方面，如结构成分，仍然难以捉摸。在这里，我们利用多维核磁共振光谱来证明安大略湖DOM中的主要结构成分。这些成分包括富含羧基的脂环族分子（CRAM）、杂多糖和芳香族化合物，这与最近在海洋溶解有机物中鉴定出的成分一致。此外，还获得了DOM的远程质子-碳相关性，这支持了源自线性萜类化合物的物质（MDLT）的存在。初步认为，大部分淡水溶解有机物本质上是脂肪族的，CRAM源自环状萜类化合物，MDLT源自线性萜类化合物。这与之前将萜类化合物作为DOM主要前体的报道一致。目前在安大略湖尚不清楚这些前体是陆地来源还是水生来源，也不清楚转化过程是通过生物和/或光化学过程进行的。
