Lack of iron is a limiting factor for plankton growth in many parts of the ocean, especially in the southern oceans and parts of the eastern Pacific. Scientists at the University of Leeds, UK, have now showed that acid in the atmosphere breaks down large particles of iron found in dust into small and highly soluble iron naonparticles; particles which can be easily absorbed and utilized by oceanic plankton.

Since plankton absorb carbon dioxide from the atmosphere, more available iron could trigger increased movement of carbon dioxide from the air to the ocean.

“This could be a very important discovery because there’s only a very small amount of soluble iron in the ocean and if plankton use the iron nanoparticles formed in clouds then the whole flux of bioavailable iron to the oceans needs to be revised,” says Dr Zongbo Shi, lead author of the research from the School of Earth and Environment at the University of Leeds.

Polluting industries that causes a high degree of acidic particles to be present in clouds can therefore strangely enough simultaneously be combating global warming.

“Man made pollution adds more acid to the atmosphere and therefore may encourage the formation of more iron nanoparticles,” says Dr Shi.

“This process is happening in clouds all over the world, but there are particularly interesting
consequences for the oceans. What we have uncovered is a previously unknown source of
bioavailable iron that is being delivered to the Earth’s surface in precipitation,” says Professor Michael Krom, the principal investigator of the research, also at the University of Leeds.