This is the third in the 2021 Monthly Online Presentation Series!
Beamline Scientist at the National Synchrotron Light Source II
Brookhaven National Laboratory
Almost all terrestrial, aquatic, and marine plants require a small amount of iron for photosynthesis. Iron is the fourth most abundant element in the earth’s crust but is extremely scarce (~31 picomolar) in seawater. Despite the scarcity of marine iron, marine phytoplankton are responsible for about 45% of the primary productivity on earth. The ocean iron budget is a critical factor in the marine “biological pump” whereby phytoplankton consume carbon from the atmosphere and sequester it in sediments.
Sampling trace concentrations of iron cleanly from the ocean while working on a steel ship presents challenges. Working at sea on a research vessel is a unique opportunity to be immersed 24/7 in a scientific community.
Most of the iron in seawater comes from terrestrial sources, suspended in river water or blown in as dust from the continents. Until recently, hydrothermal iron from submarine volcanism was considered to be only a locally important source of iron, because it was believed to oxidize and precipitate out of solution quickly. Recent synchrotron microprobe and scanning transmission X-ray microscopy (STXM) work has identified an organically-complexed iron phase in a Pacific Ocean hydrothermal plume extending thousands of kilometers from its source vent. Currently at the XFM beamline, we are analyzing a time series of samples from the Juan de Fuca hydrothermal vent field (near Vancouver, British Colombia) looking at changes in metal speciation and mineralogy as the crust migrates across the hot-spot and hydrothermal structures become disconnected and go extinct.
Please join us for an exciting evening event!
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Meeting ID: 851 2015 4436
*Bio: Sarah Nicholas is a beamline scientist at the National Synchrotron Light Source II, part of Brookhaven National Lab. Sarah did her bachelor’s degree in history and geology at Macalester College in Saint Paul, Minnesota. She completed her master’s degree at the University of Maine in isotope geochemistry and her PhD at the University of Minnesota on the solid-phase speciation of iron and arsenic in Minnesota aquifer sediments. Sarah held post-doctoral fellowships at the National University of Ireland, Galway and at SUNY Stony Brook before joining NSLS-II as a beamline scientist at the X-ray Fluorescence Microprobe (XFM) beamline in December of 2018. During the course of her PhD and postdocs Sarah spent about 6 months at sea on American, German, and Irish research vessels. Her main tasks were to collect and analyse dissolved and particulate samples for trace metals, and to describe the distribution of the radium quartet in submarine groundwater off the coast of Ireland.