Chemistry Department Seminar: Dr. Seth John ‘99

19 September 2017

“Iron nutrition in anemic seas: Using iron stable isotopes to trace
different sources of iron through the world oceans”

Friday, September 22nd, 2017
3:30 p.m. / Old Music Hall 103

Iron (Fe) is a crucial nutrient for all life, including algae living in the ocean. These algae take carbon dioxide out of the atmosphere, and form the base of the marine food chain. However, Fe doesn’t easily dissolve in seawater, and so it is often present at extremely low parts-per-trillion concentrations. Thus some parts of the ocean can be anemic, that is the growth of algae is limited by the low concentrations of iron in seawater. Small changes in iron supply to these Fe-limited regions can therefore have a massive impact on growth of algae. Over the past few years we have developed new methods to measure the stable isotopes of Fe (δ56Fe) in seawater, giving us a new tool for tracing sources of Fe to the oceans. Our new measurements of δ56Fe in the North Atlantic and South Pacific can be compared to the δ56Fe ‘fingerprint’ of different Fe sources in order to understand how Fe gets into the ocean from dust, sediments, and underwater volcanoes, and how it is transported throughout the globe to support life in the modern and ancient ocean.

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