Rapid urbanization induces organic pollution in closed water bodies and accelerates eutrophication. Dissolved organic matter (DOM), a major fraction of organic matter, causes various problems in water use. DOM sources in lakes are diverse. Moreover, DOM properties can be altered biologically and physicochemically during retention time. However, DOM in lakes consists of complex unknown substances. In the present study, high-resolution Orbitrap mass spectrometry (Orbitrap MS) was employed to determine the molecular-level composition of low-molecular-weight DOM in Lake Inba, the most polluted eutrophic lake in Japan. One-year monitoring demonstrated that the lake's DOM consisted of core components that were detected year-around and season-specific components. Although most DOM components extracted by solid phase extraction in the lake came from inflow rivers, lake-specific components were present, which could be associated with algal growth in the lake. Permanganate pretreatment was integrated with Orbitrap MS to screen for components contributing to dissolved chemical oxygen demand (DCOD_Mn), an environmental parameter used in Japan to define the water quality of lakes and reservoirs. Results indicated that only minor and highly unsaturated components were responsible for DCOD_Mn. With this approach, we were able to shed light on how the DOM composition in a eutrophic lake was shaped at molecular level, which cannot be achieved by conventional analysis.

中文翻译：

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应用Orbitrap质谱技术研究日本富营养化湖泊中溶解有机物成分的季节性变化

快速的城市化在封闭的水体中引起有机污染并加速富营养化。溶解性有机物（DOM）是有机物的主要部分，在用水中会引起各种问题。湖泊中的DOM来源多种多样。此外，在保留期间，可以通过生物学和物理化学方式改变DOM属性。但是，湖泊中的DOM由复杂的未知物质组成。在本研究中，采用高分辨率Orbitrap质谱法（Orbitrap MS）确定了日本污染最严重的富营养化湖Inba湖中低分子量DOM的分子水平组成。一年的监测表明，该湖的DOM包括检测到的全年和特定季节成分的核心成分。尽管通过固相萃取在湖中提取的大多数DOM成分都来自流入河流，但仍存在特定于湖泊的成分，这可能与湖泊中的藻类生长有关。高锰酸盐预处理与Orbitrap MS集成在一起，以筛选有助于溶解化学需氧量（DCOD）的成分_Mn），在日本用于定义湖泊和水库水质的环境参数。结果表明，只有少量和高度不饱和的组分才导致DCOD _Mn。通过这种方法，我们能够阐明富营养化湖泊中DOM的组成是如何在分子水平上形成的，这是常规分析无法实现的。