Award: OCE-2048067

This project investigated how naturally occurring radioactive isotopes of radium can be used to trace the movement of water and the transport of important chemical elements in the Pacific sector of the Southern Ocean. The work was conducted as part of the U.S. GEOTRACES program, an international effort to understand the distribution and cycling of trace elements and isotopes that influence ocean productivity and Earth’s climate.

The project focused on measurements of the four naturally occurring radium isotopes collected during two major oceanographic expeditions: GP17-OCE across the South Pacific Ocean and GP17-ANT in the Amundsen Sea, Antarctica. These expeditions sampled waters ranging from the remote open ocean to regions adjacent to rapidly changing Antarctic ice shelves. Radium isotopes are powerful natural tracers because they are released from sediments and coastal environments, allowing scientists to determine where ocean waters have recently interacted with the seafloor or continental margins and how those waters are transported and mixed.

The project successfully completed shipboard sampling, laboratory analyses, and quality control of one of the most comprehensive radium isotope datasets collected in the Southern Ocean. Preliminary results show that long-lived radium isotopes trace the widespread influence of Antarctic continental shelf waters, while shorter-lived isotopes identify areas of recent exchange between sediments and the overlying ocean. These observations are helping scientists better understand how trace elements such as iron and manganese are supplied from Antarctic continental shelves to surrounding waters, where they can influence marine ecosystems and biological productivity.

The radium isotope measurements have been integrated with the broader GEOTRACES dataset, including observations of trace metals, nutrients, hydrography, and biological properties collected by investigators from numerous U.S. institutions. Together, these measurements provide new insight into the processes controlling chemical cycling in one of the most environmentally dynamic regions of the world’s oceans.

The project also contributed to workforce development by supporting a postdoctoral researcher through participation in expedition planning, Antarctic fieldwork, laboratory analyses, and interdisciplinary data synthesis. The resulting dataset will be archived through the Biological and Chemical Oceanography Data Management Office (BCO-DMO), making these observations publicly available for future research, education, and model development.

By improving understanding of how Antarctic continental shelves supply essential micronutrients to the Southern Ocean, this project provides information that will help scientists better predict how marine ecosystems and ocean biogeochemical cycles may respond to ongoing environmental change in Antarctica.

 

Last Modified: 06/29/2026
Modified by: Matthew A Charette