Collaborative Research: Defining the Structural Basis of the Optical Properties of Chromophoric Dissolved Organic Matter

有色溶解有机物（CDOM）是一种复杂的有机物质，在水生系统中普遍存在，它不仅通过其对水生光场和卫星海洋颜色传感器对浮游植物生物量的遥感的影响，而且还通过其光化学反应发挥核心作用。虽然CDOM的光吸收和发射特性已经被广泛研究了50多年，但还没有提供令人满意的解释来解释这些材料的长波长吸收和发射行为。马里兰州大学和伍兹霍尔海洋研究所的研究人员合作提出，这种行为是由可溶性木质素前体部分氧化形成的羟基芳族供体和醌型受体之间的分子内电荷转移相互作用造成的。他们将通过将波长选择性单色（激光）和多色光漂白研究与高分辨率电喷雾电离质谱相结合来测试这一假设，以获得关于被波长选择性辐照具体破坏或产生的物种的结构信息。 吸收和荧光光谱法，凝胶渗透色谱法和木质素酚分析将提供补充的结构信息。 模型腐殖酸和木质素系统将进行检查，然后在特拉华州湾/大西洋中部海湾地区的一系列实地研究期间收集的CDOM样品。这些实地研究将提供进一步测试这一假设，通过检查的光学性质和木质素酚含量，分子大小和CDOM收集在广泛的海洋环境和季节的质谱之间的关系。这项工作将对CDOM的起源和形成模式以及其光化学性质提出基本的限制。

ABSTRACTOCE-0443263Chromophoric dissolved organic matter (CDOM) is a complex organic material found ubiquitously in aquatic systems where it plays a central role, not only through its impact on the aquatic light field and on the remote sensing of phytoplankton biomass by satellite ocean color sensors, but also through its photochemical reactions. Although the optical absorption and emission properties of CDOM have been known and studied extensively for over fifty years, no satisfactory explanation has yet been provided that can account for the long-wavelength absorption and emission behavior of these materials. Researchers at the University of Maryland and at Woods Hole Oceanographic Institution have teamed up to propose that this behavior results from intramolecular charge transfer interactions between hydroxy-aromatic donors and quinoid acceptors formed by the partial oxidation of soluble lignin precursors. They will test this hypothesis by combining wavelength-selective monochromatic (laser) and polychromatic photobleaching studies with ultrahigh resolution electrospray ionization mass spectrometry to acquire structural information on the species that are specifically destroyed or produced by the wavelength-selective irradiations. Absorption and fluorescence spectroscopy, gel permeation chromatography and lignin phenol analyses will be employed to provide complementary structural information. Both model humic and lignin systems will be examined, followed by CDOM samples collected during a series of field studies in the Delaware Bay/Mid-Atlantic Bight region. These field studies will provide further tests of this hypothesis through an examination of the relationships among the optical properties and the lignin phenol content, molecular size and mass spectra of CDOM collected across a wide range of oceanic environments and seasons. This work will place fundamental constraints on the origins and modes of formation of CDOM, as well as on its photochemical properties.