Award: OCE-1337780

Our team used NSF support to purchase an kind of advanced instrument known as an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). This family of instruments allows for the highly sensitive determination of different elements and their isotopes in a wide range of kinds of samples. Our particular team is a group of oceanographers who are particularly interested in the chemistry of elements that are present at low levels, but are nonetheless very influential on the ocean as a whole. A good example of this is iron, a metal that is required by all living things but is often very scarce in seawater and can therefore limit the amount of phytoplankton growth. Our new ICP-MS (an iCAP Q from ThermoFisher) can measure iron and most every element between lithium (atomic number 3) and uranium (atomic number 92). What is special about our new instrument is not just it's capability, but that we have connected it (hyphenated it) with two other kinds of instruments: high pressure liquid chromatograph (HPLC) and Orbitrap mass spectrometer. Through this hyphenation, we not only can measure the amount of metals like iron in a sample, but we can separate the iron present into its various chemical forms within seawater. This is critically important because not all forms of iron are as "bioavailable" to marine organisms as every other. Through separation of chemical forms prior to ICP-MS and Orbitrap detection, we can therefore identify the exact chemical form of our elements of interest. Such an approach has been attempted before, but never all at once as we are doing, and we have found this way of tackling the problem to be much superior as it eliminates uncertainties that arose using the older method. We have learned much already using our new system. For example, it is clear that iron is found in the ocean in association with very specific compounds that are synthesized deliberately by certain micro-organisms within the ocean to help them acquire iron. This was known generally before, but we are now able to identify specific compounds and associate them with specific organisms. We are also learning much about just how important these compounds are in keeping iron in seawater and how quickly they react to collect the iron in the water. We are also pursing similar studies to understand the chemistry of phosphorus, zinc and cobalt in the ocean, and are looking forward to studies of mercury as well. Last Modified: 12/04/2015 Submitted by: Carl H Lamborg