Keith Hunter is fascinated by the chemistry of the oceans and what we can learn. His research looks at trace metals in natural waters – minute amounts of metals, occurring in tiny quantities, but still extremely important – which enables us to build better models to predict climate change and to understand the speed at which change occurs.

Why trace metals?

One important reason oceanographers study trace metals is because living organisms need them to function. Sometimes, trace metals can accumulate in large and perhaps dangerous amounts, or sometimes there seem to be very few trace metals available yet somehow organisms that depend on them – such as plankton – continue to thrive. This leads scientists to wonder what special features organisms have that allow them to do this.

Keith explains that some metals act in a similar way to nutrients in the water, so he is trying to build a picture of how they behave, and he is interested in finding out how ocean chemistry changed over time. For example, the early oceans contained no oxygen (O) but plenty of iron (Fe), while modern oceans contain plenty of oxygen but very little iron because it is insoluble in the presence of oxygen. Keith looks at the role of the trace metal iron, how it is used by phytoplankton and how the phytoplankton managed to evolve and develop systems to bind iron.

Dust and phytoplankton?

Keith also looks at how iron gets into the oceans. An interesting suggestion is that it is derived from desert dust – the dust settles on the ocean, giving plankton that are close to the water surface an important supply of iron. Deserts are sensitive to climate change, and there is a possibility that changes in weather patterns could affect the way dust is distributed – and this could have a drastic impact on the availability of iron in the ocean. This is a problem because phytoplankton form the basis of ocean food webs – around half of the world’s photosynthesis is performed by these tiny but important creatures.

    Published 27 August 2009