Award: OCE-1234191

In this project, we measured the rare earth elements (REEs) and neodymium (Nd) isotopes in a transect across the Eastern Equatorial Pacific (EEP), as part of a larger international GEOTRACES effort to map the distributions of such trace elements and isotopes in the global oceans. In conjunction with the other data collected in this and other GEOTRACES cruises, these REE and Nd isotope data will be used to 1) understand the processes that control trace element distributions in the oceans and 2) better constrain the deep circulation of this region. (An example of such an elemental map of these data is given in Figure 1.) With respect the first issue: Our data will be used to better understand the sources and sinks of potential micronutrients such as iron, which has potential controls over nutrient utilization and ecosystem health. The EEP is a globally vital fishery, which is based on a healthy ecosystem that depends on micronutrients. Like the rainforests, the paradox of the EEP is that the apparent prolific natural growth is actually based on a rather fragile balance hinging on strong chemical recycling of nutrients. Our data will be used to try and develop a better model of where the likely points of failure are in this system that may result from human or natural pressure. With respect to the second issue: Deep ocean water constitutes a vast repository of both heat and dissolved gases (e.g., carbon dioxide). Understanding how this deep water flows in the basin, how long it resides at depth and where it may resurface are very challenging questions. But these answers will have critical and direct bearing on issues such as future changes in greenhouse gases and possible mechanisms of carbon sequestration, and how the oceans will become more corrosive in the future. Our data will be used to attempt to better understand the circulation paths of the deep ocean, and how we may be able to reconstruct past changes in this circulation, to help us build models of future change. The data that we have generated are rather esoteric in nature, in no small part because these measurements are complicated and difficult to make. Our efforts in this project are multi-institutional, and nest in the greater multi-national efforts to generate a global database of these elements and isotopes. As such, the data is rich with intricacies and nuance - both internal to the EEP sections, but more so through comparison with other ocean basin data. The complexity of the science increases as the databases grow, but this is the path towards a more holistic understanding of the processes governing marine biogeochemistry. The EEP data collected in this project will continue to move us towards this ultimate goal. This project has supported research science at Oregon State University, including a lab technician and undergraduate assistants. This project helped to continue the strong inter-institutional collaborations - both nationally and internationally - that foster scientific and cultural understanding and cooperation. The project also helped to support the US sea-going science venture, which makes manifest the sense of exploration and curiosity characteristic of US science. Last Modified: 05/15/2018 Submitted by: Brian A Haley