Award: OCE-1756402

Intellectual Merit

This project tested the hypothesis that diffuse low-temperature hydrothermal venting plays a critical role in ocean biogeochemical cycling, particularly as a source of stabilized dissolved iron to the deep ocean, and hence plays an important but previously overlooked role in the global biogeochemical iron cycle. We completed a state-of-the-art ship and autonomous vehicle field program, to identify plumes of both diffuse (low-temperature) and high-temperature hydrothermal discharge along the Southern East Pacific Rise. Emissions from multiple sites of low-temperature hydrothermal venting and several high temperature vent sites were sampled for analysis of dissolved and particulate metals, the chemical and physical form of iron, methane and hydrogen gas, and the conservative hydrothermal tracer helium-3. The data addressed two hypotheses, first that the population of active hydrothermal discharge sites along mid ocean ridges is greater than previously estimated, with many sites hosting only low-temperature flow and second, that low-temperature hydrothermal venting is conducive to the stabilization of dissolved iron, facilitating its export to the ocean interior and ultimately to the iron-deficient surface ocean where it impacts primary production. The major finding from this work was that diffuse systems contained a higher fraction of stable, soluble dissolved iron, and we were able to use this finding to help us detect low temperature vents. We also hypothesize that this higher fraction of soluble iron was in part supported by the higher siderophore concentrations in those samples.  

Broader Impacts

The project has provided training and professional development opportunities for several graduate students, including Laura Moore and Jessalyn Davis, as well as two undergraduate students, Dylan Vecchione and Patrick Monreal. Both are now graduate students at the University of Washington. The project results have been disseminated to the scientific community through conference presentations and one completed dissertation. 

Last Modified: 08/29/2024
Modified by: Randelle M Bundy