Collaborative Research: The chemistry of lignin's photochemical transformation in the environment: implications for global carbon cycling

在这个由化学部环境化学科学项目资助的项目中，老自治领大学的帕特里克·哈奇博士、普林斯顿大学的萨蒂什·米内尼博士和俄亥俄州州立大学的克里斯托弗·哈达博士采用多学科方法研究木质素，木质素是一种复杂的有机聚合物，沉积在许多植物的细胞壁中，使它们变硬和木质化。 木质素是一种地球上丰富的有机生物聚合物，它为将植物中的碳回收到环境中提供了起点。 在这个项目中，研究人员探索了木质素分子重排的途径，以形成土壤，水和沉积物中存在的分子。 一名博士后助理，研究生和几名本科生接受培训，结合联合收割机地球化学，基础分子研究，先进的分析技术和复杂反应途径的现代计算建模。 这项培训为这些未来的科学家提供了跨学科的经验。 包括大学生和高中生的参与，包括多元化的招聘。在本研究项目中，木质素受到活性氧（ROS）的氧化降解，部分重组和降解，形成腐殖物质。这些腐殖物质可以有效地螯合木质素衍生的碳，这与木质素完全氧化为二氧化碳并导致温室效应的理论相反。本研究课题合成和天然木质素氧化分解的活性氧在水溶液中的铁物种的存在下，模仿环境氧化。该研究采用傅里叶变换离子回旋共振质谱，多维液体和固体NMR，以及基于同步加速器的X射线吸收光谱来辨别分子转化途径。 该研究还提供了有关光化学和ROS影响地球大型碳库中陆地碳循环的途径和幅度的新信息，从而影响陆地系统和海洋的化学。

In this project funded by the Environmental Chemical Sciences program of the Chemistry Division, Drs. Patrick Hatcher of Old Dominion University, Satish Myneni of Princeton University, and Christopher Hadad of The Ohio State University employ a multidisciplinary approach to study lignin, a complex organic polymer deposited in the cell walls of many plants, making them rigid and woody. Lignin is an Earth abundant organic biopolymer that provides the starting point to recycle carbon from plants into the environment. In this project, the researchers explore pathways for the molecular rearrangement of lignin to form the molecules present in soil, water and sediments. A postdoctoral associate, graduate students, and several undergraduates are trained to combine geochemistry, fundamental molecular studies, advanced analytical techniques, and modern computational modeling of complex reaction pathways. This training provides these future scientists with an interdisciplinary experience. Undergraduate and high school engagement, including diversified recruitment, is included.In this research project, lignin is subjected to oxidative degradation by reactive oxygen species (ROS) to partially reorganize and polymerize to form humic substances. These humic substances may effectively sequester lignin-derived carbon in contrast to the theory that lignin is completely oxidized to carbon dioxide and contribute to greenhouse warming. This research subjects both synthesized and natural lignin to oxidative decomposition by ROS in the presence of aqueous iron species, mimicking environmental oxidation. The study employs Fourier transform ion cyclotron resonance mass spectrometry, multidimensional liquids and solids NMR, and synchrotron-based X-ray absorption spectroscopy to discern molecular transformation pathways. The research also provides new information regarding both the pathways and magnitude with which photochemistry and ROS affect the cycling of terrestrial carbon among Earth's large reservoirs of carbon, impacting the chemistry of terrestrial systems and oceans.