Award: OCE-1736875

This award was to participate in the GEOTRACES GP15 research cruise, which went from Alaska to Tahiti in 2018 and investigated trace elements along the way. This particular award was to analyze a suite of dissolved metals in the seawater, focusing on their surface ocean distributions and the element scandium. Intellectual Merit: We measured the dissolved concentrations of iron, manganese, copper, nickel, zinc, cadmium, lead, scandium, yttrium and lanthanum along the surface transect from Alaska to Tahiti, and at five "super stations" that were 32-depth profiles from surface to bottom. In the surface samples, we found most metals had higher concentrations nearshore, with the exception of lead. Lead decreased in concentration in the samples closest to the Alaska margin that corresponded with lower salinity and expected river input. Lead is also the only metal to show a significant surface concentration increase in the 25-45N latitude range, which corresponds to Asian aerosols. Cadmium was the only element measured to show elevated concentrations at the equator due to equatorial upwelling. Manganese showed a concentration peak at 5N which may correspond to the North Equatorial Counter Current. Several elements (nickel, copper, yttrium, and lanthanum) all increase steadily in concentration from 35N to the Alaska margin (~55N). This transition at 35N corresponds with the subtropical front. Unique among the elements analyzed here, scandium showed a concentration peak from 10-30N. This peak aligns with the deepest isotherms along the northern part of the transect, and may reflect the lower biological activity in this region. A similar trend between scandium concentration and deep isotherms was found in the North Atlantic (Till et al., 2017). This is the first time the trend has been observed elsewhere, and seeing it in the North Pacific as well suggests it may be a broad trend across ocean basins. Broader Impacts: This work involved many undergraduates playing a large role. In 2018, the PI and undergraduate Kezia Rasmussen went to Seattle to load the ship and help build a trace metal clean "bubble" that the scientists onboard the ship used to work without contaminating the samples at sea. Undergraduate Rasmussen was also hired full time in summer 2018 to help with cruise preparations. In summer 2019, undergraduate Robert "Ben" Freiberger was hired full time through this award to analyze the samples from the cruise. He also participated in a student exchange between Humboldt State University (now called Cal Poly Humboldt) and lead-PI Jessica Fitzsimmons' research group in Texas A&M: undergraduate Freiberger went to Texas A&M for a week to learn some of their analytical methods and experience a research-focused university; Fitzsimmons' graduate student Nathan Lanning travelled to Humboldt State University for three days to learn our analytical method and to see an example of a primarily undergraduate institution that participates in significant research projects, which he was considering as a potential career path. In February 2020, the PI and three undergraduates (Freiberger, Jacob Begorre, and Cristina Tusei) presented on the data from this award at the Ocean Sciences Meeting in San Diego. Then in spring and fall 2021, undergraduates Peter Bright, Daniel Sabo and David Zeitz worked on data interpretation, and their contributions are expected land them authorship in an upcoming paper. Two of these undergraduates have remained in the field of chemical oceanography after graduation: Freiberger is currently a research technician at Scripps Institution of Oceanography, and Bright is a graduate student at Oregon State University. Others have gone on to graduate school in different fields: Tusei is a graduate student in environmental resources engineering, and Zeitz is accepted to a Ph.D. program in chemistry at UCLA. Additionally, it was PI Till's first NSF Award, and served to set the groundwork for her next major research award, which was the Cottrell Scholar Award (2020-2023). Last Modified: 02/01/2022 Submitted by: Claire P Till