Pyrite nanoparticles are a kinetically stable iron source to the ocean

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Deep sea high-temperature hydrothermal vents spew metals leached from rocks in the seafloor up into the ocean as jets of concentrated fluids. When these hot metal-charged liquids hit cold seawater at the bottom of the ocean as they exit the vents, recent research has shown that nanoparticles of Fe, Fe-Cu, and other metal sulfides form and are wafted upward into the water column. This research investigates these particles and how far they are able to travel from their site of origin. It involves complementary fieldwork at three deep sea hydrothermal vents on the mid-Atlantic Ridge and laboratory experiments. The fieldwork allows collection of new vent fluid samples containing dissolved and nano-crystallized nanoparticles. Lab work consists of characterization of these natural particles and a study of their chemical makeup, in addition to experiments designed to determine their resistance to oxidation in seawater and fluids that range in pH from 7 to 8. A primary goal of the work is to discover naturally occurring mechanisms that allow these metal nanoparticles to resist aggregation, settling, and oxidation in the ocean, allowing them to be transported long distances at abyssal ocean depths where they form essential nutrients for chemosynthetic organisms. The broader impacts of the work include a strong workforce development piece that reaches from the high school to the graduate student level. Both undergraduates students and a high school teacher will be involved in the research and the teacher will also accompany the scientists to sea. The work has impacts outside of its field in that it will (1) dramatically improve our understanding the distribution and sources of essential chemosynthetic nutrients in the deep sea and (2) improves our understanding of the behavior of anthropogenically generated metallic nanoparticles in the ocean.