My main role at MBARI is using FIA techniques to measure trace metals in seawater. We are especially interested in iron due to it's importance as a micronutrient for phytoplankton growth. Sources of iron to the surface ocean include upwelling, runoff and atmospheric deposition. However, iron is very insoluble in seawater and can limit phytoplankton growth even in coastal areas. The Southern Ocean around Antarctica is one of the largest areas of the worlds oceans believed to be productivity limited due to extremely low concentrations of dissolved iron.