Award: ANT-2023230

This project funded the management and implementation of a 65-day research cruise (“GP17-ANT”) to the Amundsen Sea sector of the Antarctic margin (Figure 1) in November 2023-January 2024.  This project was part of the International GEOTRACES Programme (www.geotraces.org), which is a coordinated global effort to measure the distribution of “trace elements and their isotopes” (TEIs) in the global ocean. Trace elements are any element on the periodic table that is found in very small quantities.  The trace elements measured by the GEOTRACES program include those that are essential nutrients for life in the ocean, such as iron, cobalt, and zinc, those that are contaminants and toxic, such as lead and mercury, and those that trace specific inputs, such as aluminum for inputs from land.   Isotopes are variations of elements that differ in their atomic mass, and can be stable or radioactive.  The stable isotopes (such as for nitrogen and iron) are useful for identifying sources and processes affecting that element.  The radioactive isotopes (such as beryllium and thorium) provide a natural clock by which rates of important processes can be quantified.  The distribution of these TEIs provide a fingerprint of key biological, chemical, physical, and geological processes that may be difficult or impossible to measure directly.  The simultaneous measurement of a suite of over a dozen TEIs on every GEOTRACES cruise provides exquisite constraints on oceanographic processes.  The GEOTRACES programme is thus providing us new insights about how the ocean works. 

The Amundsen Sea is the location of the fastest melting Antarctic glaciers.  This rapid glacial melt is expected to impact ocean circulation and biogeochemical cycles.  Bringing the GEOTRACES toolbox to studying this region helps to understand the influence of glacial melt on the nutrient and toxic trace elements in the region and the consequences for biological activity, and our stable and radioactive isotope tools help us to trace the source and rates of important processes in this region.

The U.S. GEOTRACES GP17-ANT cruise included 23 individual NSF awards from scientists across the United States, each focusing on a different aspect that fulfilled the GEOTRACES mission.  The goal of this management project was to coordinate and collect all water, sediment, and suspended particle samples needed by the 23 groups of scientists, and to collect and measure important oceanographic parameters such as temperature, salinity, nutrients, oxygen, and phytoplankton pigment concentrations required by most groups to provide the environmental context for their specific TEI measurements. Altogether, 35 scientists on board spent 65 days at sea (Figure 2), sampled from 21 “stations” over the Amundsen Sea continental shelf, 3 over the continental slope, and 3 off-shelf (Figure 1), collected several tens of thousands of liters of water for measurements of TEIs in seawater and filtered several hundreds of thousands of liters of water for measurements of TEIs in marine particles.

After the cruise, the goal of the management team was to facilitate the sharing of data and collaboration between the 23 groups of scientists to ensure that the entire cruise was more than the sum of its parts.  We have started to do did this through virtual seminar series, coordinated special sessions at conferences, and data workshops.  Our results will be published in highly regarded scientific journals by the participants of the cruise, and data from this project will be released to the public and made freely available. 

An early-career journalist was supported to embed with us on the cruise.  She reported on us and her experience through a cover story in EOS (https://eos.org/features/confined-at-sea-at-the-end-of-the-world) and a podcast series on Scientific American (https://www.scientificamerican.com/podcast/episode/could-iron-from-melting-glaciers-affect-global-climate/).  This cruise also provided an opportunity for 15 graduate students or postdocs to conduct oceanographic research at sea, training the next generation of oceanographers.

Last Modified: 11/18/2025
Modified by: Phoebe J Lam