Pathways and regulation of transformation of low molecular weight carbon compounds in subseafloor sediments from the Guaymas Basin (Gulf of California)

这项研究将探索地球上最大的碳库之一，海洋沉积物中的碳循环，位于海洋底部。随着时间的推移，这些碳通过相互作用的地质，化学和生物过程逐渐再循环。该项目将记录这些过程中的每一个如何转化来自瓜伊马斯盆地（加州湾）的海洋沉积物中的碳。这种设置提供了一个机会，研究碳循环在广泛的化学和温度梯度，提供了一个机会，梳理除了调节海洋沉积物中的碳循环的因素。该项目将调查海洋沉积物在全球碳循环中的作用。这些研究目标代表了全球环境变化时代的关键科学优先事项。关于外联活动，这位科学家将与吉姆·图米教育公司合作，继续制作“扎克和莫莉历险记”教育录像系列。 在这种情况下，视频将记录这项研究的结果及其更广泛的意义。 这位科学家还将为教师编写一本学习指南。 录像带和学习指南都将分发给教育工作者。 一名研究生和一名本科生将作为该项目的一部分得到支助和培训。 在瓜伊马斯盆地（加州湾）的地下沉积物提供了一个可访问的窗口，调查碳循环在一个动态的，但易处理的海洋环境。这项工作将研究如何加热地下沉积物影响生产，消费和命运的低分子量溶解有机碳。该研究将跟踪关键碳物种的命运-包括甲酸盐，乙酸盐和甲醇-因为它们通过微生物介导的过程进行处理。样本是在2019年9月至10月的国际海洋发现计划第385次考察期间收集的。在研究船上进行了一些实验，并将在实验室进行其他实验。该研究将限制的转化和命运的低分子量碳底物的直接速率，池的大小和稳定同位素测量耦合到热力学建模和实验室实验的组合。研究的主要课题包括：（1）地下沉积物中有机化合物的主要产生模式是什么？(2)沿着地球化学和温度梯度的主要甲烷生成途径是什么？(3)微生物驱动的碳循环过程的温度限制是什么？(4)有机化合物的命运如何随着地球化学和/或温度梯度的沿着变化？该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

This research will explore carbon cycling in one of the largest carbon reservoirs on Earth, marine sediments, located at bottom of the ocean. This carbon is recycled gradually over time through interacting geological, chemical, and biological processes. This project will document how each of these processes transforms carbon in marine sediments from the Guaymas Basin (Gulf of California). This setting offers the chance to study carbon cycling across a broad range of chemical and temperature gradients, providing an opportunity to tease apart the factors regulating carbon cycling in marine sediments. This project will investigate the role of ocean sediments in the global carbon cycle. These research objectives represent key science priorities in a time of global environmental change. For outreach activities, the scientist, in collaboration with Jim Toomey Education, would continue the “Adventures of Zack and Molly” educational video series. In this instance, the video would document results from this study and its broader significance. The scientist also would create a learning guide for teachers. Both the video and the learning guide would be disseminated to educators. One graduate and one undergraduate student would be supported and trained as part of this project. Subsurface sediments in the Guaymas Basin (Gulf of California) offer an accessible window for investigating carbon cycling in a dynamic, yet tractable, marine environment. This work will study how heating of subsurface sediments affects the production, consumption, and fate of low molecular weight dissolved organic carbon. The research will track the fate of key carbon species – including formate, acetate, and methanol – as they are processed through a gauntlet of microbial-mediated processes. Samples were collected during Expedition 385 of the International Ocean Discovery Program in September-October 2019. Some experiments were conducted on the research vessel and additional experiments will be conducted in the laboratory. The study will constrain the magnitudes of transformation and the fate of low molecular weight carbon substrates using a combination of direct rate, pool size, and stable isotopic measurements coupled to thermodynamic modeling and probative laboratory experiments. Key topics for investigation include: (1) What is the dominant production mode for organic compounds in subsurface sediments? (2) What are the dominant pathways of methanogenesis along geochemical and temperature gradients? (3) What are the temperature limits of microbially-driven carbon cycling processes? (4) How does the fate of organic compounds change along geochemical and/or temperature gradients?This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.