Award: OCE-1441969

Intellectual Merit Iron is an essential nutrient for phytoplankton, required for photosynthesis and respiration. In the oceans, low iron availability limits phytoplankton growth over large areas (up to 40%) of the surface ocean and plays an important role in the global carbon cycle. In the modern ocean, iron solubility is too low to support phytoplankton growth and iron-binding molecules called organic ligands play a critical role in keeping iron in solution and determining how much iron phytoplankton can access. The primary objective of this work was to measure the distributions of iron-binding organic ligands in the eastern tropical South Pacific as part of the US GEOTRACES Eastern Pacific Zonal Transect. These project results represent the first large scale full water column data set for iron-binding organic ligands in the Pacific and provide new insight into ligand sources and sinks in the oceans. These data also highlight distinct differences in ligand characteristics between the Atlantic and Pacific Oceans. Project results have been submitted for publication in a peer-reviewed journal and presented at national science conferences in the U.S. and Canada, in university seminars, and an international synthesis meeting. Broader Impacts Education, outreach and training were integral to project activities. Project activities have been highlighted in a collaborative webinar for educators hosted by the Center for Ocean Sciences Education Excellence (COSEE) and GEOTRACES (http://cosee.umaine.edu/programs/webinars/geotraces/). Project results and activities have been incorporated into education materials for graduate level oceanography courses at the University of South Florida (USF) and have been shared with middle school girls as part of annual mentoring activities with the USF Oceanography Camp for Girls. Project data have been made publicly available via the Biological and Chemical Oceanography Data Management Office (www.bco-dmo.org) and will be included in the upcoming 2017 GEOTRACES Intermediate Data Product. The project provided training for two research technicians, an undergraduate intern from an underrepresented group and two graduate students at the University of South Florida. Last Modified: 05/26/2017 Submitted by: Kristen N Buck