Iron is quickly becoming recognized as a limiting nutrient for the growth of marine phytoplankton in many parts of the worlds oceans. These are areas where their is an abundance of sunlight, nitrate and other nutrients, but phytoplankton growth is limited by the lack of iron. This is especially true in the open ocean where there is no land to provide a source of iron. Iron is the 4th most abundant element in the earths crust but is extremely insoluble in seawater and very difficult to measure at low levels.  Iron is necessary for the production of chlorophyll, the plant pigment used to gather energy from sunlight and  produce biomass. We are beginning to realize that episodic inputs of iron due to rain, wind, upwelling and other such events can control not only phytoplankton growth, but species composition and potentially atmospheric CO₂ (greenhouse gas) levels, and may have been responsible for pre-industrial (before burning of fossil fuels) glacial/interglacial periodicity. The sensors group realizes the need to make frequent, if not continuous measurements of iron and monitor the phytoplankton and atmospheric CO₂ response to this iron. Currently we use a shipboard mapping and laboratory based FIA method for the determination of low level iron. We are currently developing an in situ sensor to measure iron. It is our hope to put this sensor on moorings to get a constant and complete picture of variable iron concentrations.

COASTAL IRON

Current studies include: