Cycling of Dissolved Organic Matter in the Pacific and Indian Oceans Using Radiocarbon

海洋溶解有机碳老化的控制方法海洋溶解有机碳大部分以溶解形式存在。令人惊讶的是，这种溶解的有机碳的年龄是数千年，尽管它被认为是在海洋表面的光合作用过程中形成的。对碳的年龄的一种解释是碳在海洋中循环所需的时间。加州大学欧文分校（UCI）的研究人员将利用碳-14同位素研究太平洋、南大洋和印度洋溶解有机碳的老化情况。这项工作对于了解未来人类活动产生的碳将如何在地球上分布非常重要。该项目将支持两名研究生和两名本科生的工作，为他们提供实践经验，为他们成为科学家和教育工作者做好准备。两位研究生都将参与各种教育活动。他们还将在夏季为研究生、技术人员、博士后和研究人员讲授一门关于碳-14在生态学和地球系统科学中的应用的短期课程。UCI是一个为西班牙裔服务的机构（27%的本科生是西班牙裔），60%的UCI学生是第一代家庭代表。本研究将研究太平洋、南大洋和印度洋深度剖面中溶解有机碳（DOC）的浓度、同位素（14C、13C）和分子组成。这些信息将有助于确定世界海洋中DOC循环的主要控制措施。该项目将测试循环是最深水域（3500米）DOC循环的主要控制因素的假设。研究还将探讨可能影响深水（2000-3000米）DOC年龄的两个替代过程：(1)表面衍生颗粒的溶解和(2)热液喷口和侧翼的古碳输入。设计用于表征部分DOC的光谱和光谱测量将在水面和深水上进行。研究结果将被纳入DOC循环的逆模型，以确定控制海洋DOC循环的主要过程。DOC可能作为人类活动产生的过量二氧化碳的汇，海洋中难降解DOC池的大小可能随着环流减缓而增加。测量表层和深海中DOC的14C年龄对于了解全球碳循环如何随着地球气候变化而变化非常重要。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Controls on the Aging of Marine Dissolved Organic CarbonMost of the organic carbon in ocean water is in the dissolved form. Surprisingly, the age of this dissolved organic carbon is thousands of years old, even though it is thought to form during photosynthesis in the surface ocean. One explanation for the age of this carbon is the amount of time that it takes for carbon to circulate through the ocean. Investigators at the University of California Irvine (UCI) will investigate the aging of dissolved organic carbon in the Pacific, Southern and Indian oceans using C-14 isotopes. This work is important for knowing how carbon produced from human activities will be distributed on Earth in the future. This project will support the work of two graduate and two undergraduate students, providing hands-on experience that will prepare them for careers as scientists and educators. Both graduate students will be involved in a variety of educational activities. They will also help teach a short course on applications of C-14 in Ecology and Earth System Science for graduate students, technicians, postdocs and researchers during summer. UCI is a Hispanic-serving institution (27% of undergraduates identify as Hispanic), and 60% of students who attend UCI are first generation family representatives. This study will examine the concentration, isotopic (14C, 13C) and molecular composition of dissolved organic carbon (DOC) in depth profiles from the Pacific, Southern and Indian Oceans. This information will help to determine the main controls on DOC cycling in the world’s oceans. The project will test the hypothesis that circulation is the primary control on DOC cycling in the deepest water (3500 meters). The research will also investigate two alternative processes that could influence the age of DOC in deep water (2000-3000 meters): (1) dissolution of surface-derived particles and (2) input of ancient carbon from hydrothermal vents and flanks. Spectroscopic and spectrometric measurements designed to characterize a portion of the DOC will be performed on surface and deep water. Results will be incorporated into an inverse model of DOC cycling to determine the main processes controlling the DOC cycle in the ocean. DOC may serve as a sink for excess carbon dioxide produced from human activities and the size of the refractory DOC pool in the ocean could increase as circulation slows. Measuring the 14C age of DOC in the surface and deep ocean is important for understanding how the global carbon cycle will change as the Earth's climate shifts.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.